ESP value modified.

[Quell]

Hello.
I hooked an address of a function withing my own process, but now when i run it i get this error:

Run-Time Check Failure #0 - The value of ESP was not properly saved across a function call.  This is usually a result of calling a function declared with one calling convention with a function pointer declared with a different calling convention.

I was testing this on Vista and wondering how can i bypass this?Note that thsi is only valid in debug builds.
Thx