Hi sama

band in ntc of same size it means somewhere in pcr components there is contamination of template. Try to find out where you went wrong. I suggest you to do pcr with +ve sample using all new  pcr components  and old component in which your getting contamination. Set ntc separately in both cases. If you there is no band in ntc where u used new pcr components but reverse is the case in ntc with old pcr components then your old pcr component are contaminated. If ntc appears in both cases then there is handling error in case of new components but either of the case in case of old component. If you further want to investigate which component is contaminated then try to set the assay by changing each component at once.

Good luck.....