Why are PCR bands relatively weak and "smearing" but the alignment marker bands are sharp when running samples on the QIAxcel System and QIAxcel Advanced?
FAQ ID -1837

High or very low salt concentration could lead to the described appearance when running samples on the QIAxcel System and QIAxcel Advanced. Make sure QX DNA Dilution buffer has been used to dilute your samples. Dilute your samples 1:2 in QX DNA Dilution buffer and re-analyze.