Button used to close glossary in course is behind the glossary

I have an 'X' button on the glossary to be used to close the glossary in the course (executes the hide advanced action) however the button image is hidden behind the glossary when the course runs.  I have it arranged to be placed on top and the selected option for Place on Top within the properties.

Running captivate 8

What am I missing with this?

Thanks,