Steering Wheel Problem

I tried to create my own external steering wheel.
I took a picture from google and scaled the image till it had the optimal size, then i replaced the front view of the steering wheel with GIMP by editing a stwheel.tex.
I replaced the front view very exactly, but after starting GP4 there was a little mistake: the center of the steering wheel is correct but around the center everything is black and also the site of the arms are black. :S

Does anybody know a solution or did anybody have the same problem? Is there something special I have to observe ?


Greetings Mexinho

How does the alpha channel looks like?

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My Grand Prix 4 Files
I'm a total dick. How many people can say that?

I don't really know what you mean with this because I'm no expert.
But I looked for the alpha channel in GIMP and there you can see what is selceted in the alpha channel and - sorry if it's the wrong answer to your question - everything without the 4 elements which are used in the race are belongs to the alpha channel.

Is there someone who can tell me how to create an external steering wheel or someone who can explain to me what I did wrong ?