Not sure if this will help or not as I've not used that particular wheel, but, when installing a clients DD wheel with Project 2 cars a few weeks I go I had terrible trouble with it. I kept getting the error multiple inputs detected.
The way I solved it (and it worked first time) was to unplug the pedals and any other loadcell/potentiometer based input device from the PC. Restart PC2 and then assign the steering wheel, then calibrate it. Then come out of PC2 and plug everything in as normal, then return to Controller assignments and do the throttle, brake and clutch etc, then calibrate them.
So I guessed the issue was that the signal from the load cell pedals I used on that sim, was noisy enough to give the game multiple input signals when trying to detect the steering.
Hope you solve it. Please let me know if you try this and it works.