I have the same wheel. Had it in the box for 2 years and now the adapter is missing. I have the same problem you do, EVERYTHING works fine but the FFB, so I have bought an adapter with exactly the same input and output. The adapter has a green light but the wheel should also have a green light, which is still not working. The ffb doesnt work either.

P.S: I have enabled FFB in BOTH the game and the wheel's drivers.