Strange problem with _x and _y

i have a crop tool in flash. the pictures are sometimes bigger that the popup window and i have a fit to window button that is resizing my movie clip that contains the loaded picture into another film with startDrag actions on it.

when i’m resizing it i try to place at _x=0 and _y=0 but don’t work at all. it happens nothing. another thing, tracing _x and _y result 0, but tracing bounce (xMin, yMin) works fine.

export to flash 6 as2.

if help i’ll post the sample here but tomorrow.