My image doesn't display in the pop up

Hi all.

I am using RoboHelp 11.

I have inserted an icon image, then right clicked on the image and inserted a hyperlink.

I want to create an Auto Sizing Pop Up with a link to another image, but as soon as I enter the file path I want to link to, the Auto Sizing Pop Up becomes disabled and only Display in Frame is selectable.

Please can anyone assist.