Trouble exporting

Sometimes I can find the problem in the dialog of the ‘Exception while exporting’ dialog, but sometimes it just buffalos me. I’ve attached a pdf of my problem - maybe I missed something simple.

I have tried renaming the local cssimages folder and option copying the one from the var folder in to it, but I still get the same exception message.

I’ve attached an image with all the pertinent info.

Can anyone see something obvious, or tell me how to export this page?

I’m using RW 6.3.8 on Yosemite.