I'm working now on western blot and trying to detect Kifc1, but it gives me a dark background and I washed for 2 hrs and used 5% BSA-TBST blocking. The same problem of high background is very dark.
If you have washed it for 2 hours and still see backround, it is strange. Like mentioned previously reduce the concentration of your secondary, It is also better to add a little quantity of 5% BSA-TBST with your secondary antibody to increase the efficiency.