C++ struct to C# With Delegate

[Gezan]

Hi all,

I have a question. The struct below is used to handle the callback of a Unmannaged c++ dll.

struct CALLBACK
{
	typedef BOOL (*CALL_AP)	(LPVOID pThis, GT_HANDLE hFrom, GT_ERROR Error, GT_CALLBACK_TYPE dwType, LPVOID pData); 
	BOOL IsVaild()	{
		return (m_pCall != NULL);
	}
	LPVOID				m_pThis;
	CALL_AP				m_pCall;
};

I tried to translate this struct but probabaly the problem will lie here in the tranalsation of the struct.

    [StructLayout(LayoutKind.Sequential)]
    struct CALLBACK
    {
        public delegate bool CALL_AP(IntPtr pThis, UInt32 hFrom, GT_STATUS Status, GT_CALLBACK_TYPE dwType, IntPtr pData);
        public bool IsVaild()
        {
            return m_pCall != null;
        }
        public IntPtr m_pThis;
        public CALL_AP m_pCall;
    }

but if i use this code the callback function will run 1 time and crash with a unhandled win32 exception