Rack Joint in CATIA

Well, If u have created two separate mechanisms viz. revolute and prismatic then it will never simulate. Create only one mechanism, e.g Consider three parts, 1,2 &3 If one is a disc having hole at its center, 2&3 is square rib and 4th one is small shaft. Mount the disc on the shaft,create surface contact(external) between disc& rib 2, again create surface contact between rib 2 & rib 3. Now 1)create new mechanism1. 2)Then create revolute joint between shaft and disc. 3)Then create prismatic joint between rib2 & rib3. 4) Now click on rack joint select revolute and prismatic joint from the specification tree, click the check box angle driven for revolute. 5) Set the shaft as a fixed part. 6)create rigid joint between shaft and rib 3. Now you get the message "mechanism can be simulated. click on the simulation icon, change the angle value,press play button, u will observe, disc is rotating, shaft and rib3 is stationary,and rib 2 is moving forward/backward according to the selection of the angle tab.