rubber edpm roof completely seperated loose

While I agree mostly with rjxj, I disagree on the contact cement part. You don't want a cement that sticks on contact if the Dicor cement lets you move or slightly slide or even pick up and lay back down the material once it's laid down. Otherwise you might wind up with a huge bubble, wrinkle or a huge gap down the cut seam.

I can't see your roof, but you might be better off cutting a large T or even a capital I in the membrane so it's easier to peel back and get under with the glue.