b16d28c9__ChIP_Help___Novus_Biologicals__Issue
[Phase] Cross-linking [Recommendations] Under cross-linking can prevent the disassociation of protein-DNA complexes in the following steps and result in poor yield. Over cross-linking can mask epitope sites crucial for antibody binding, prevent proper chromatin shearing, and inhibit the successful uncross-linking of the complex in subsequent steps. If using paraformaldehyde, ensure that it is freshly prepared. [Issue] 
Too much/little cross-linking
Chromatin Immunoprecipitation Troubleshooting: ChIP Help | Novus Biologicals
Issue