C++ Build error was not declared in this scope

Im writing a small program in C++. I have created 2 files "Main.cpp" and "openni_grabber.cpp". As you can see from the code I'm starting a thread from the main. Once I try to build I get an error message: 'SimpleOpenNIProcessor' Was not declared in this scope.

Where in the code do I need to declare SimpleOpenNIProcessor?

Main.cpp

#include <pcl/io/openni_grabber.h>
#include <pcl/visualization/cloud_viewer.h>

int main()
{
    SimpleOpenNIProcessor v;
    v.run();
    return(0);
}

openni_grabber.cpp

#include <pcl/point_cloud.h>
#include <pcl/point_types.h>
#include <pcl/io/openni_grabber.h>
#include <pcl/common/time.h>

class SimpleOpenNIProcessor
{
    SimpleOpenNIProcessor()
    {
    };

    public:
    void cloud_cb_ (const pcl::PointCloud<pcl::PointXYZRGBA>::ConstPtr &cloud)
    {
        static unsigned count = 0;
        static double last = pcl::getTime ();
        if (++count == 30)
        {
            double now = pcl::getTime ();
            std::cout << "distance of center pixel :" << cloud->points [(cloud->width >> 1) * (cloud->height + 1)].z << " mm. Average framerate: " << double(count)/double(now - last) << " Hz" <<  std::endl;
            count = 0;
            last = now;
        }
    }

    void run ()
    {
        // create a new grabber for OpenNI devices
        pcl::Grabber* interface = new pcl::OpenNIGrabber();

        // make callback function from member function
        boost::function<void (const pcl::PointCloud<pcl::PointXYZRGBA>::ConstPtr&)> f =
            boost::bind (&SimpleOpenNIProcessor::cloud_cb_, this, _1);

        // connect callback function for desired signal. In this case its a point cloud with color values
        boost::signals2::connection c = interface->registerCallback (f);

        // start receiving point clouds
        interface->start ();

        // wait until user quits program with Ctrl-C, but no busy-waiting -> sleep (1);
        while (true)
        boost::this_thread::sleep (boost::posix_time::seconds (1));

        // stop the grabber
        interface->stop ();
    }
}