Runtime Impersonation

[Snig]

Hi all

I need to implement Runtime (Conditional) Impersonation in one of my ASP.NET
Pages.

If I use the <identity impersonate="true" /> in web.config file, it works
fine.

But in code, while I try to Impersonate I get Win32 error. I am using
"Logon" Win32 API for get a specific token. But this API is returning error
1314 : A required privilege is not held by the client

I tried to resolve it by assinging the most probable Security priviledges to
the "ASPNET" account by "Local Security Policy" snap-in. But nothing worked.

Can anybody please help me ?

Thanx in advance.