PyImport_Import在python模块中导入子模块时失败

我有这样的CPP代码：

void callPython() {
    Py_Initialize();    
    PyObject* sysPath = PySys_GetObject("path");
    PyList_Append(sysPath, PyUnicode_FromString("/jarvis_repo/src/cpp/packages/jarvis/nlp/"));
    // Load the module
    PyObject *pName = PyUnicode_FromString("my_mod");
    PyObject *pModule = PyImport_Import(pName);
    if (pModule != NULL) {
        std::cout << "Python module found\n";       

        PyObject* pFunc = PyObject_GetAttrString(pModule, "my_func");
        if(pFunc != NULL){
            PyObject_CallObject(pFunc, NULL);
        } else {
            std::cout << "Couldn't find func\n";
        }
    }
    else {
        PyErr_Print();
        std::cout << "Python Module not found\n";
}     
    Py_Finalize();
}

我在同一目录中还有两个文件my_mod.py和test.py，/jarvis_repo/src/cpp/packages/jarvis/nlp/如下所示：

my_mod.py

from test import coreDM
def my_func():
    print("my_func() got called")
    coreDM()

test.py

class coreDM():
    def __init__(self):
        print("Initialized test")

    def print_message():
        print("Hello from coreDM")

当from test import coreDM与coreDM()从省略my_mod.py，PyImport_Import工作正常，并打印my_func() got called，否则返回NULL。任何想法为什么会发生这种情况？提前致谢！

错误信息：

ImportError: cannot import name 'coreDM'
Python Module not found