A little problem with my walls

I have a slight problem with my walls when I use hittest.

In my game I have a sort of maze thing, which is navigated by a guy I nicknamed “Joe”

I’m using hittest to stop Joe passing through the walls, and was having sucess untill I split the walls in half, so that the charecter wouldn’t pass through it.

The wall looks like this: (if it was a diagram!)

-------------- Top movie clip
-------------- Bottom movie clip

I did this to stop the charecter passing through the walls, but when I try to pass through top movie clip, it lets me through, even though I coded to push the charecter away

the top wall code:


onClipEvent (enterFrame) {
    if (this, hittest(_root.Joe)) {
        _root.Joe._y = _root.Joe._y - 12;
    }
}

The bottom code works fine (it’s the same, but with a + sign)

Any ideas? or even better, is there another way?

Thankyou!