I'm trying to copy a structure to a byte array.  I get a failure on the
Marshal.StructureToPtr() function. The structure which is as follows:

[StructLayout(LayoutKind.Sequential, Pack = 1)]
public struct CONNECT_STRUCT
 {
   public byte Format;
   public short sNumBytes;
   [MarshalAs(UnmanagedType.ByValArray, SizeConst=25)]
   public byte[] szDatabase;
   public byte cCommand;
   [MarshalAs(UnmanagedType.ByValArray, SizeConst=32)]
   public byte[] szVerification;
 }

CONNECT_STRUCT pConnectStruct = new CONNECT_STRUCT();

pConnectStruct.Format = 2;
pConnectStruct.cCommand = 4;
pConnectStruct.sNumBytes = (short)Marshal.SizeOf(pConnectStruct);
pConnectStruct.szDatabase = StrToByteArray("MY_DATABASE");      
pConnectStruct.szVerification  = StrToByteArray("ABCDEFGHIJKLMNOP");

int len = Marshal.SizeOf(pConnectStruct);

byte[] arr = new byte[len];
IntPtr ptr = Marshal.AllocHGlobal(len);
Marshal.StructureToPtr(pConnectStruct, ptr, true);  <===FAILS

It fails with: Type could not be marshaled because the length of an embedded
array instance does not match the declared length in the layout.

I compared "len" with the actual size of the structure and it is correct.
Any ideas?

Thanks,
Terry