in AS2, it's _x and _y

PHP Code:
onClipEvent(enterFrame){ 
    
trace(rock._x); 
    
trace(rock._y); 
    } 
in AS3, it's .x and .y (like you have). however, there is no onClipEvent in AS3, so you must be in AS2.

btw, this is the AS3 board.