different kinematic behavior with mechanism and manipulate

Hello,
i have an assembly with mechanism (ans assembly of mechanism), 2 sub assembly (flexible with mechanism). each sub assembly and mechanism works fine (Gear train & Motor) . In top assembly, each command of sub assembly works fine too. When i add a prismatic between sub assembly (Motor with Entry axle of Gear Train) commands are blocked, but top assembly can move with manipulate (under constrain).

Do you have any idea to make it works with mechanism?
Best regards