There can be different causes for Nero to report the wrong writing speeds available. Updating Nero can solve your problem.
The version of Nero that came with my burner (Liteon 48x24x48x) didn't work very well for me (I could either write at 48x or at 4x!). So I updated this version (www.ahead.de) and it worked, all writing speeds that should be available where available.
What's your problem exactly? Are speeds up to 32x available, or only 32x? If there are more speeds, but all 32x or lower, available, this is probably the SmartBurn feature of your drive, detecting 32x as maximum speed for your media. If not, I think that updating Nero to the latest version (.20) is a wise thing to do.
(btw, I'm moving this thread to the appropriate forum )