Problemm to test a MC container

Hi,

i load JPGs into a mc, when i click on a button.
after this, when i rollover on the JPG, my menu must move on Y axis.

all work very well with the FIRST JPG.

the problem is :

when i click on other menu button, it unload the JPG, cool… but unfortunately,
when i rollover on the empty MC container, my menu always move on Y axis !!! ( i shouldn’t move, because the MC container is empty ! )

what’s the problem ?