Rename DLL and it no longer works as a plugin

I have a plugin system which uses DLLs. The DLLs load as expected unless I rename a DLL then that DLL no longer loads. If I rename the DLL it fails to load on LoadLibraryA() because it returns NULL. For instance the project which creates the DLL creates a DLL named test.dll it will load properly. If it go into explorer and rename that DLL to test1.dll it will no longer load because it fails on LoadLibraryA(). My code has no hard coded DLL names in there so I'm unsure why the application will no longer load valid plugin DLLs unless they have the name that it was originally created as.