Does anyone have problems with degraded DNA and primer dimers after isolation of DNA from buccal swabs with QIAGEN DNeasy Blood and Tissue Kit (250)?

I isolated mtDNA with DNeasy Blood & Tissue Kit (250) from buccal swabs and I got good results for a month. But after two months of DNA storage at -20 °C, pcr loaded on 2% Agarose gel shows...

16 December 2014 2,031 3 View