Type Lib Conversion problem

Question

I tried using the tlbimp.exe utility of .NET sdk to import a type library(a C API) to a compatible assembly code. I was succesful at doing that and was able to Add a Reference to the namespace i assigned. However when I tried to get the function of the imported assembly code its not there!!The enumtypes, deftypes, constants were present except for all the functions innate to the library. Has anyone encountered the same scenario? Should i program it now in unmanaged code using .NET's interop services if im unsuccessful of doing the latter one?