Windows

I am having a VC++ Project that uses a method which is defined in some DLL file and I have added the generated .LIB file in the Link Tab in Project Settings. There are many such .LIB files linked through that tab.
Now I want to go through the whole definition of that function which I am calling. But the Debugger doesnt take me to the definition of that function in any of the .LIB file (i.e., the .CPP file Implementing the function). But the function is surely executed as it returns a Boolean Variable. So can you kindly tell me how to debug such functions. I tried to place breakpoints in the project's .cpp files which makes the DLL file, by opening that project in different instance of VC++. But the debugger doesnt stop over there.