I just ran two reels of film through Ilfosol S that I bought in the middle of November and they both came out blank. It was the very last of the bottle so Im thinking that maybe the developer expired in concentrate? I have both a fresh bottle of Ilfosol S and a small bottle of Rodinal (yes, I'll be joining that cult soon! ) so it's not like I need the shots for production, but man is it annoying. Ilford's site said "4 months in tightly capped half full bottles." Is my hypothesis reasonable or is it more likely an ID-ten-T error?