Non-specific binding of control antibodies for ChIP-seq

[jdub]

I am having trouble with a lot of non-specific binding with both my negative and positive control antibodies. I am using an anti-RNA Pol II positive control and rabbit IgG negative control and using primers for GAPDH and ZNF333. I get equivalent levels of amplicons at both loci with both antibodies. The concentrations used are what was recommended for IP...25 ug/mL for anti-RNA Pol II and 100 ug/mL for IgG.

Does anyone have any suggestions on where my ChIP might be going wrong?

[jdub]

By the way, I have tried two different cell lines and gotten the same result with each.