Axes with hand held driving controller and usb adaptor

[Gradius]

http://www.marashop.de/media/Ultraracer2.jpg

I've bought this hand held controller for PSX, which I use with my PC with a USB adaptor. It's great but I have a problem with the axes. The  wheel is considered as axis X, which appears centered and you can move left and right in the controller panel. One of the analogue buttons is considered as axis Z, which appears as a red bar which is filled when the button is pressed to the max. The trigger is called rotation Z and it's the same way as the analogue button. These 3 elements work perfectly as independent axes, and are correctly used by the games, as well as the rest of digital buttons. What I don't understand is why one of the analogue buttons is not working, and also the reverse movement of the trigger, which should work as braking. This must be an issue with the adaptor and the number of supported axes. I don't know if the trigger should be one combined axis or two different axes. I opened up the controller and I could only see one potentiometer for the trigger. I've tried withe another adaptor and I got one more working axis (that analogue button). The config of the axes with this adaptor is different: the wheel appears as axis Z as a red bar filled to the middle and which goes up and down as you move the wheel left and right. The analogue buttons are recognized as axis X and Y and the trigger as rotation Z. Again moving the trigger on the other direction makes no effect. Actually, all this is not a problem because I have more than enough with 3 axes: wheel for steering, the trigger for accel and one analogue button for braking. However, I'd really like to have the backwards movement of the trigger for braking. Do you know how could I fix this? Could I install other drivers for the adaptor so as to have all axes working? My adaptors are called 3 in 1 pc joybox, psx+n64 usb converter, and smartjoy. I'm using the first of the 3. Apart from these issues, the controller is fantastic, very precise and the games feel much more playable than using an analogue gamepad. It's no substitute for a real wheel and pedas, but it's good for a quick game when you don't have time or don't feel like installing a wheel on your desktop.