You don't have -any- code to show us...?
Are you using AS2 or AS3?
Change all references to y coordinates to x coordinates would be my guess.
General notice: from now on, I would like to ask everyone to put [AS2] or [AS3] (corresponding to the version of actionscript you are using on your project) in front of their post titles when the question is actionscript related! Please help us help you faster. Thank you.