Loading a DLL from s-function

I am trying to load a dll to use in simulink. I have coded up an s-function that calls code that interfaces to the dll. This interface or glue layer code has been debugged and successfully run under Visual Studio. I am now trying to get it working in conjunction with a simulink model. I step through the code using VS2005 as the debugger. It loads the dll and then fails on the first call to GetProcAddress. I have run DependecyWalker and the function/method is there so it should find it. I compile the glue layer and the s-function using the legacy_code call. Any ideas?

Thanks!