RT-PCR

[banuy]

I am using SuperScript First-Strand Synthesis System for RT-PCR. I performed the reaction with control RNA and it worked. I tried 4 different primer sets for 4 different genes. 3 of the primer sets which amplify smaller than 500 bp fragments are working but 1 primer set which should amplify a 2 kb fragment is not working. Are there anyone who faced with problems with moderately long product amplifications?