Captive backs, I have been sitting here messing around trying to get a 1/2" back held captive in a 3/8" dado,set in from the back edge of the cabinet 3/4 of an inch But when i go to the back screen to fill out the joint info it has the top blocked out. Am I missing something somwhere else. what are the settings to get that silly back held captive. It is quite slippery