Levels don't work in my installation of CS 5.1. The dialog comes up but adjustment don't change the image. I reinstalled CS 5.1 but that didn't fix things. Any ideas on what I can do?
Could you please post a screenshot with the Layers Panel visible?
Are you viewing at 100% (Actual Pixels)?
Do you have Preview checked in the dialog?
OMG - preview was unchecked, as was my attention. Thanks for that. I never conciously uncheck preview in any dialog and have assumed over the years that it was the default mode. Lesson learnt...