Amplification Failure of Unknown Reason - (Mar/19/2003 )

Hi Everyone,
I am trying to amplify a viral gene for sequencing purposes for several times and I was able to amplify it from 3 samples only, the most unusual thing that I was not able to amplify the sample twice with the same conditions I tried to change annealing temp, template conc, even designed new primers but still I cant solve this problem

Some viral templates need 5% DMSO for expansion. You could try that.