I'm using VB. (I have other posts on this project, but with other issues.)

The function signature in the documentation looks like this:
//Specify a function to be called when the camera is disconnected from the
system. After setting a notification function, the callback mechanism can be
disabled by passing NULL for inNotificationFunc.
KPDCStatus KPDCSetCameraEventNotification ( KPDCCameraRef inCameraRef,
KPDCCameraEventNotificationFunc inNotificationFunc, void *inUserData);

In the demo code the do this:
// Set up the camera event notification
// The camera will send an event to notify you that the contents of the
// active folder has changed.  The most likely cause for a folder content
// change event is when the camera had written a new image to the
// directory. If you look for this event, you'll know when the image is
// ready for retrieval after the shutter has been released.
theStatus = theProcs.SetCameraEventNotification(theCamera,
CameraEventHandler, NULL);

And CameraEventHandler looks like this:
////////////////////////////////////////////////////////////////////////////////
//    Description:
//    Callback function to handle camera events.  If we receive a
KPDCFolderContent
//    event we will set the global flag g_fYouveGotAPicture to true.
//
//    Parameters:  All defined in the *KPDCCameraEventNotificationFunc
//                    callback data type in KProDCSDKTypes.h
//
////////////////////////////////////////////////////////////////////////////////
void KPDCCALLBACK CameraEventHandler(
           KPDCUInt32  inEvent,         // The event code, see
KPDCCameraEvents
           KPDCUInt32  inParam1,        // Events may have an integer
parameter
           const char  *inParam2,       // Events may have a string parameter
           KPDCUInt32  inParam2Length,  // Length of the string parameter
           void        *userData )        // Could be a pointer to a C++ object
{
    if( (inEvent == KPDCAddFile) || (inEvent == KPDCFolderContent) )
    {
        SetEvent(g_hImageReady);
    }
}

I am trying to write my wrapper in VB. This code seems to be passing the
name/address of an event handler to the unmanaged code. Is this true? None of
what I've posted here was in the unmanaged code, it's all from a demo that is
written in C++. I don't have the source to the unmanaged code, just the
function information. (As seen in my first few lines here.)