slideme app - Install button not working but cancel is?

Hi All - I'm sorry for such a basic question but need some help.
I have an at&t note 4 and I am able to download the app and then get to the install screen where there is a INSTALL button and a CANCEL button. The cancel button highlights and works but the INSTALL button doesn't do anything. I have the box checked to allow unknown sources.
Any idea what is going on or how to fix it?

Thank you for you help