What you will do when you do not get any error message but your web application simply hangs. That is what happened to me last week when I tried the following.
As our application design requires us to use one of the validation API engine which was written on C(so basically all I have is a dll) and I tested calling the functions using small windows application using DllImport for each functions and it works without any problem. But when I try to use the same Dll in my asp.net web application, it hangs with the first call which is init function call. I tried giving the dll path as a hardcoded path like C:\<application directory\bin>validation.dll in my dllimport funciton call but did not help. I am wondering it has something to do with ASPNET account security. So I gave full control for ASPNET account for my application directory and still my application hangs. I even tried copying the dll file into system32 directory but no hope.
Anybody faced this earlier?