huge dot appears at the centre of every of my bands - (Oct/17/2011 )

Help! huge dot appears at the centre of every of my bands I don't know why. The only suspect i'm thinking is contamination..but how could it be restricted to travel at only the centre of the band?

It looks to me like you've pierced your well with the end of the pipette tip while loading the sample creating a funny shape in your bands. Next time try no to put the tip so deep in the well.

just my 2 cents!

oh I see. I think that must be problem.I recalled that I wanted to make sure that the DNA I was loading does not escape too much out of the well so i purposely place the tip slightly deeper(not pierce the bottom of well though). Thankx alot:)