You would need to detail your set up a little more. First off you can only fill a space to any size if the elements can scale. Either proportional changing the height of your banner region or by positioning them individually with preference in scale and pinning section. By the looks of it you are using the proportional scale. The problem I see is that the slides are not moved out of the way according to the scale.
This version uses proportional scale and changes the height according to the width. Pinning is irrelevant in such a setup, at least in the content. Again, don't pin the containers for the slider or the slides, though.