Help!PCR problems.

[sl1nn at cc.usu.edu]

I am having problems with PCR amplification of a small fragment of cloned DNA.  I
I have designed my own primers, using Oligo 4.1, and according to the program I
am using the right temperatures for the primers. I have varied tha conditions
several times with the same results.  The negative control (without
template) of my two primers always shows a 250 bp band.  Both primers are
22-mers and the dimers would not be that large. In additon, when I have the
template present I am only seeing the same band. I have checked the primers for
contamination using HPLC, and they check out at the right size and with only
one peak.  Does anybody have any idea why I am getting this result?  I'm going
crazy trying to fix the problem.   Thanks in advance.