C++ to C# using DllImport

[t_msreddy]

Hello!
I am working on .NET compact framework. I have a device driver in
C/C++. I need to write a wrapper in C# for it.

So I used DllImport statements for all the methods that I want to use
and are there in the dll. I am unable to write a DllImport definition
for one of the functions defined in the DLL

Here is the Function prototype in dll:
DWORD WINAPI RFID_EnableTriggerCallback(HANDLE
*phTrigger, HANDLE hReader, BOOL bFlag, void
(*pTriggerCallbackParam)(DWORD dwTriggerStatus), DWORD
dwTriggerMask);

The 4rth parameter is the function name that would be invoked when
this event occurs. Basically our device has a Trigger which when
pressed invokes this method (RFID_EnableTriggerCallback method) which
in turn calls the user defined method pTriggerCallbackParam).

The way I thought I would do in C# was like this:

[b:a386e70009][DllImport("kernel32.dll")]
public static extern UInt32 RFID_EnableTriggerCallback(ref IntPtr
phTrigger, IntPtr hReader, bool bFlag, IntPtr callBackFunctionName,
bool dwTriggerMask);[/b:a386e70009]

But I think, the way i am specifying the 4rth parameter is wrong.
Please tell me the correct way to do it.

Thanks
Madhu Tera