weak bands - western blots (Oct/07/2010 )

Hi!

can someone tell me how my center bands of westerns are weak?. All the bands are the same thing and volume the same also. I have attached the films.
It was one westrn cutted in the middle where you can see i wrote WH. In the western to the right its clearly visible the difference of dark. All the westrn are the same. At the centre of membrane the bans are weak.

Thank you

uneven distribution of solutions during processing may be the cause of this (if everything else is equal).