Loading on PAGE - (Jul/08/2010 )

Any body has any idea on why DNA samples loaded on Native PAGE dont migrate all at the sam level?why this would happen? any suggestion?

different size, salt content of the sample, tilted gel (not level),...

show us a picture

No, they are all with the same size see the attached... Is it because the running buffer is not ok or APS is not fresh enough?

bubbles under the center of the gel (between the plates) could cause this.