- Be sure to use an annealing temperature determined by the nearest neighbor method (or Tm Calculator ).
- Use fresh high-quality nucleotides. It is important to avoid dNTP mixes that contains dUTP.
- Use more template. Sample concentration may be too low.
- Template DNA may be damaged. Use carefully purified template.
- Lengthen extension time.
- Increase cycle number.
- Optimize enzyme concentration.
- Denaturation temperature may be too low. Optimal denaturation temperature for most templates is 98°C or higher.