Pm52 problems printing light screens

We run a PM52 four color and are having trouble with light screens and images that are ghosted into the background of the page. The image appears on the plate but wont show up when on press. It seems to be anything lighter than about 10%. We have tried new blankets and packing with no luck. HELP!!

 

I cant think of any mechanical reason why ink would not get onto the sheet even on light screens. I would look and see with a loop if ink is getting on the blanket. What kind of plates are you usingand what is your chemistry like? Maybe the ink is getting washed out of the light screen areas on the plate.