I'm trying to interface to InfoZip's Zip32.dll from VB.Net code.

The DLL expects a structure with all its input parameters:

typedef struct {
   int  argc;              // Count of files to zip
   LPSTR lpszZipFN;        // Archive file name
   char **FNV;             // file names to zip up. Think of this an argv
} ZCL, _far *LPZCL;

int WINAPI ZpArchive(LPZCL);

I was trying to implement this as a structure in VB.Net too, but either it
isn't possible or there's something wrong with my approach:

Private Structure ZipFileList
   <MarshalAs(UnmanagedType.I4)> Dim nFiles As Integer
   <MarshalAs(UnmanagedType.LPStr)> Dim ZipFile As String
   <MarshalAs(UnmanagedType.LPArray, ArraySubType:=UnmanagedType.LPStr)> _
       Dim FileNames() As String
End Structure

I get an exception, "Can not marshal field FileNames of type ZipFileList:
This type can not be marshaled as a structure field."

Is there a way to make this work?