Problems with densitometry!....for WESTERN BLOTS

[Gerard]

Hi,

I've just made a strange discovery when developing by blots.  I found that
when I expose my blots to film, after using ECL, the bands that I get for
shorter exposures aren't always "lighter" than the bands I get for longer
exposures.  They are sometimes darker!!!!  This also happens in reverse
(of course).  I was just wondering if anyone else has had this problem
and, if so, what solutions are there.  Thanks.

Gerard