I really need help on this because I lost my hopes to correct the problem.
I am using Office Communications Server 64bit libraries. There are 3 dlls I use in the pro
I had this problem with ASP.NET IIS and after trying everything, I enabled 32-bit for my app pool and restarted the application pools. Then it worked.
In the IIS7 Manager: Application Pools -> DefaultAppPool -> Advanced Settings -> Set "Enable 32-bit applications" to true.
Also make sure the correct .Net version is selected.
I also set the ISAPI 64bit to allowed under "ISAPI and CGI Restrictions", but I'm not sure if that helped.