defeating antidecmpiler tricks

["ggk_28" <ggk_28@...>]

Hi,

 I am trying to decopile a vb3 program using DoDi's VB3 
Decompiler..but after the program(exe) is loaded into the Decompiler 
it gives the following message :

'Contains unknown structure!' and 'Severe errors may cause the 
decopiler to crash' and then it displays a messagebox "Cheat"..and 
exits the decompiler..

What's wrong here ?.Can someone help me ?.For other vb3 programs the 
decompiler is working fine.

Gaurav.