PCR problems

[Cecilia Alaniz]

Hi:

I am trying to amplify a 1850 fragment via PCR using Vent and I been
having lots of problems because I am using a template which is a PCR
product itself, I used it diluted 1/10 and the results are only smears,
also I tried with the touchdown protocol (smear), with diferents Mg
concentrations (smears), with new and old reactants (smears) and I am
really desperate because I can not think in what is wrong with the
reaction (or maybe is me).    Please if someone can give any advised I
will grateful.

Thank you in advanced.
Cecilia