I am trying to pass a structure into an unmanaged C function.  This
structure contains an array of another structure.   The internal structure
contains an array of integers.  This nested structure is an in parameter
only.  How can I do this?  I have tried several ways of doing this and I
always get an interop exception.  I doesn't seem to like the nested
structures/arrays.  What is the right way to do this?

Here is an example of what I am trying to do...

[StructLayout(LayoutKind.Sequential, Pack=8, CharSet=CharSet.Ansi)]

internal struct INPUT {

public int iMode;

public int iNumBases;

[MarshalAs(UnmanagedType.LPArray, SizeConst=20)]

public nested_Base[] tBase;

public struct nested_BaseInfo {

public int iID;

[MarshalAs(UnmanagedType.ByValArray, SizeConst=10)]

public int[] iNAIDs;

}

public int iNumCol;

[MarshalAs(UnmanagedType.ByValArray, SizeConst=10)]

public int[] iColIDs;

public float fSize;

};

[DllImport(m_strDLLName)]

private static extern int Foo( ref INPUT Input );