Can not reference a Dll that worked earlier.

Question

I am trying to change the Terminal Services settings programmaticly. I learned that you must use tsuserex.dll. Being c# i ran tsuserex through tlbimp and created TSUSEREXLib.dll then registered it with regasm. I got it working and wrote a framework program with it as a prof of concept. However today after I made some changes when I run my program I get the error

Unable to cast COM object of type 'System.__ComObject' to interface type 'TSUSEREXLib.IADsTSUserEx'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{C4930E79-2989-4462-8A60-2FCF2F2955EF}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)).

it thows the exception on the line

IADsTSUserEx iad = (IADsTSUserEx)((DirectoryEntry)user.GetUnderlyingObject()).NativeObject;

This exact line worked fine in the test project. I know user is a valid UserPrincipal, Googleing I found this is usually just needs the dll re-registered, but even after unloading and reloading it it still will not work. What am I missing to cause my dll to stop working.

Answer 1

You almost certainly need to re-register your TLB on the target machine. What likely happened is you have your assembly, interface or type GUID not hard coded in the application and hence it's changed on every rebuild. So after rebuilding and deploying your type no longer matches up with the previously registered TLB.

Answer 2

The correct answer is that I am a idiot for not reliseing that my build environment did change. I moved to a new workstaion that was windows 7 corprate instead of server 2003 when i started on the project. Win7 corp does not have tsuserex.dll in its system.