Button not working in Android application

I am new to Android and trying to implement a simple button, which should display a message in a Toast (eventually it's going to be used to create an account). But nothing happens when I press the button, no errors are displayed on the logcat either so I must be missing something obvious but I can't find it!!

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.laptop.whatsfordinner" >

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <!--Splash Screen -->
    <activity
        android:name=".Splash"
        android:label="@string/app_name"
        android:screenOrientation="portrait"
        android:theme="@android:style/Theme.Black.NoTitleBar" >
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />

        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
    </activity>

    <activity
        android:name=".MainPage"
        android:label="@string/app_name" >

    </activity>

    <!--Register User -->
    <activity
        android:name=".RegistrationActivity"
        android:label="Register User">
    </activity>
</application>

<!--  Internet Permissions -->
<uses-permission android:name="android.permission.INTERNET" />

</manifest>

registration.xml

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:weightSum="1">

    <!-- Name Label -->
    <TextView android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/reg_title1"
        android:paddingLeft="10dip"
        android:paddingRight="10dip"
        android:paddingTop="10dip"
        android:textSize="17sp"/>

    <!-- Input Name -->
    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="2.08"></LinearLayout>

    <EditText android:id="@+id/inputName"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dip"
        android:layout_marginBottom="15dip"
        android:singleLine="true"
        android:background="#ffffff" />

    <!-- Username Label -->
    <TextView android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/reg_title2"
        android:paddingLeft="10dip"
        android:paddingRight="10dip"
        android:paddingTop="10dip"
        android:textSize="17sp"/>

    <!-- Input Username -->
    <EditText android:id="@+id/inputUsername"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dip"
        android:layout_marginBottom="15dip"
        android:singleLine="true"
        android:background="#ffffff" />

    <!-- Email Label -->
    <TextView android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/reg_title3"
        android:paddingLeft="10dip"
        android:paddingRight="10dip"
        android:paddingTop="10dip"
        android:textSize="17sp"/>

    <!-- Input Email -->
    <EditText android:id="@+id/inputEmail"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dip"
        android:layout_marginBottom="15dip"
        android:singleLine="true"
        android:inputType="textEmailAddress"
        android:background="#ffffff" />

    <!-- Password Label -->
    <TextView android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/reg_title4"
        android:paddingLeft="10dip"
        android:paddingRight="10dip"
        android:paddingTop="10dip"
        android:textSize="17sp"/>

    <!-- Input Password -->
    <EditText android:id="@+id/inputPassword"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dip"
        android:layout_marginBottom="15dip"
        android:singleLine="true"
        android:inputType="textPassword"
        android:background="#ffffff" />

    <!-- Button Register-->

    <Button android:id="@+id/btnRegister"
        android:layout_width="136dp"
        android:layout_height="37dp"
        android:text="@string/reg_button1"
        android:enabled="true"
        android:layout_gravity="center_horizontal" />

    </LinearLayout>

RegistrationActivity.java

 package com.example.laptop.whatsfordinner;


    import android.app.Activity;
    import java.util.ArrayList;
    import java.util.List;

    import org.apache.http.NameValuePair;
    import org.apache.http.message.BasicNameValuePair;
    import org.json.JSONException;
    import org.json.JSONObject;

    import android.app.Activity;
    import android.app.ProgressDialog;
    import android.content.Intent;
    import android.os.AsyncTask;
    import android.os.Bundle;
    import android.util.Log;
    import android.view.View;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.Toast;



    public class RegistrationActivity extends Activity {


    // Progress Dialog
    private ProgressDialog pDialog;

    JSONParser jsonParser = new JSONParser();
    EditText inputName;
    EditText inputUsername;
    EditText inputEmail;
    EditText inputPassword;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.registration);

        // Create button
       Button btnRegister1 = (Button) findViewById(R.id.btnRegister);

        // button click event
        btnRegister1.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                // creating new account in background thread
                Toast.makeText(RegistrationActivity.this, "Example action.",      Toast.LENGTH_SHORT).show();

            }
        });
    }

Registration.java

package com.example.laptop.whatsfordinner;

import android.app.Activity;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.support.v4.widget.DrawerLayout;

public class Registration extends Fragment {
    /**
     * The fragment argument representing the section number for this
     * fragment.
     */
    private static final String ARG_SECTION_NUMBER = "section_number";

    /**
     * Returns a new instance of this fragment for the given section
     * number.
     */
    public static Registration newInstance(int sectionNumber) {
        Registration fragment = new Registration();
        Bundle args = new Bundle();
        args.putInt(ARG_SECTION_NUMBER, sectionNumber);
        fragment.setArguments(args);
        return fragment;
    }

    public Registration() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.registration, container, false);
        return rootView;
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        ((MainPage) activity).onSectionAttached(
                getArguments().getInt(ARG_SECTION_NUMBER));
    }

    @Override
    public void onDetach() {
        super.onDetach();
    }
}

What am I doing wrong?