Catia v5 user defined axis

[tattymotor]

I am modelling form blocks that that are used in Automotive body in White engineering. They have to be positioned on the cad data surface and eventually trimmed for NC manufacture. I want to create a user defined axis on the cat part so that I can position the part by changing the co-ordinates. However when I create the axis system on the part and then move the cat part the axis system moves to the new co-ordinates but the cat part stays put. I am sure I need to lock the axis to the cat part in some way but I don't know how. Could someone please explain this procedure to me.

Many thanks