Lining up Problems

1

Why is it that when I try to mask an image that is bigger than the content box so that it fits within the borders of the box, the image does not sit flush against the edges? There is a gap between the image and the border lines though the mask set right against the edges of the box’s outline. I have zoomed in to verify that there is no gap between the mask and the box’s inside edges. on the stage it looks fine when the mask is applied but when I play the movie, there are gaps between the image and the iside edges of the box. Someone please help, thx.