Troubleshooting
Before trying anything here, make sure your game is completely clean (unpatched, untranslated), since some patches fiddle with the code and may affect functionality. If nothing works, please open a ticket or email me.
Make sure DirectInput is not disabled.
Also, make sure twinhook.dll is not compiled with the Debug target, as it adds debugging code which mangles the hooks for the DirectInput8 hook.
Additionally, make sure you do not have a controller plugged in, since this messes with DirectInput.
If the game requires the dx8->dx9 patch, make sure it is applied (dxd8.dll and enbconvertor.ini).
Make sure the game actually runs without twinject first (make sure you have DirectX 9 installed, preferrably the package from 2010). Also make sure that the correct game executable is set in twinject.ini (create this file if it does not exist, there's an example config in the Releases).
Disable the debug visualization if it is enabled.