Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

I am trying to call an unmanaged DLL within c#. I have the DLLs source so I know what the variables are within C, I just can't seem to build the DLLImport function correctly. Can someone help me out here

The C function
int UULoadFile (char *filename, char *fileid, int delflag)
{
.......
}

The C export
#define _ANSI_ARGS_(c) c
int UULoadFile _ANSI_ARGS_((char *, char *, int));

My DLLImport
internal const String UUDEVIEW = "uudeview.dll";
[DllImport(UUDEVIEW, EntryPoint = "UULoadFile", SetLastError = true)]
internal static extern int UULoadFile([MarshalAs(UnmanagedType.LPStr)]string filename, [MarshalAs(UnmanagedType.LPStr)]string fileid, int delflag);

Everytime I call UULoadFile I get,

An unhandled exception of type 'System.AccessViolationException' occurred in NZB Queue.exe

Additional information: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

My DLLImport
internal const String UUDEVIEW = "uudeview.dll";
[DllImport(UUDEVIEW, EntryPoint = "UULoadFile", SetLastError = true)]
internal static extern int UULoadFile([MarshalAs(UnmanagedType.LPStr)]string filename, [MarshalAs(UnmanagedType.LPStr)]string fileid, int delflag);

can't it be like this

My DLLImport
internal const String UUDEVIEW = "uudeview.dll";
[DllImport(UUDEVIEW, EntryPoint = "UULoadFile", SetLastError = true)]
internal static extern int UULoadFile(string filename,string fileid, int delflag);

Thanx,

Ch.T.Gopi Kumar.