repeting PCR failing the reaction - (Nov/10/2008 )

Good morning dear all.
More time ago i've done (twice) a PCR with two specific primers (GC% respecivaly 51 and 65 for FW and RW)and obtained my expected product.
Now I've repeated the same PCR for more times but without success.
why? I've used also new reagents and other cDNA as template but the reaction fail.
the problem are the primers?
who can help me?

thank u very much

Fralab

Could you please send a picture of the gel and pcr parameters (cycles and reagents concentrations).

Problem can be with your cDNA template, could be degraded. Hard to say without more information.