Security Exception when run asp.net under sharepoint site

Hello,

I create asp.net page using vs.net2003. It calls win32 function
(P/Invoke). It works fine. But when I deploy it under sharepoint site
and exclude path, it produces security exception when calling win32
function. It should come from sharepoint because in other website in
the same machine in works fine. I try to trust by assembly using
wizard but it does not help.

Thanks,
Theewara

.