reason for the browning of the silver gel - (Jan/08/2009 )

Hi everbody,
Silver staining worked so well last year but suddenly yesterday i followed the same protocol but unfortunatley my gel turned brown and it took long time to develop approximately 15 minutes...could anyone of u help me know what could be the reason...thank u

Are you using the old reagents for staining?sometimes it happens to me also and the reason for this could be sodium thiosulfate, which is used for sensitization.if gel turns brown but not getting developed then either your sod. thiosulfate or silver nitrate solution might be bad