I am using this Ab at a dilution of 1:5000.  This is lot CFZ151011.
  I am doing Ag retreival for 25 minutes in a steamer and have yet to have a
problem with background.  I do not think increasing your washes will cause the
ab to wash off.  Once the binding has occured, it is very strong.  The dako
protein block is not causing the problem, if anything this should help eliminate
some of the background.

Christine Klein
MD Anderson Cancer Center