TFApplication is in TFCom. Perhaps the wrong version of TFCom is registered?
You can search your registry for "TFApplication" and see if the path points to your 8.11 installation (see attached screen capture)
To search the registry, go to Start>Run and keyin regedit and press ‘ok'
Then goto Edit>Find and keyin TFAplication and press ‘find next'
It should find TFCom.TFApplicationList under "ProgID". There should be another folder called "LocalServer32", this should show the path to your microstation (ustation) installation. If it's not right or does not exist, you can repair it using tfcomregister.
Can you search your installed Bentley folder for tfcomregister.exe?
e.g.
cd "c:\program files\Bentley\" dir /s /b tfcomregister.exe
Run this exe with the -? Switch
usage tfcomregister -tfregserver|-tfunregserver e.g. tfcomregister -tfregserver c:\PROGRA~1\Bentley8.9.0\
Run this executable with the -tfregserver switch and pass the installed Bentley folder as the second argument,
If you installed Structural to "c:\program files\Bentley\", then your command line should look like "c:\ PROGRA~1\Bentley\ tfcomregister.exe" -tfregserver c:\PROGRA~1\Bentley8.9.0\
Similarly, there's an stfcomregister.exe w/ an -stfregserver argument