Music CD's not working after being burnt

Ive got Nero 7 (Nero 8 is a p.i.t.a) and an EZ Dub burner. For some reason, my cd's that I burn won't play in any car stero. I have music cd's (52x and 40x) and I know I'm burning them right. Can any one tell me what is wrong and how to fix it? Thanks in advance.