Accessing a VC++ MFC dll from VB.NET

EXTERN_C void FAR PASCAL EXPORT CreateGUID(BSTR* bstrGUID,short ID)
{
	CString strGUID;
	AfxBSTR2CString(&strGUID, *bstrGUID);
	ACNCreateNewGUID(strGUID,ID);
	*bstrGUID = strGUID.GetBuffer() ;
	//return strGUID;
}		

Public Class Form1
Public Declare Function CreateGUID Lib "GUIDDll.dll" (ByRef sStr As String, ByVal iNum As Short)

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim exstr As String = ""        
        MessageBox.Show(CreateGUID(exstr, 10))
    End Sub
End Class