Hi David, sorry I didn't mean to ignore your question in the other thread. Thought you were suggesting maybe that was the problem with Jo.
If it's the old dashboard, here you go:
When adding a photo to your listing, keep in mind the following guidelines:
Photos must be in one of these formats: JPG, GIF, PNG, TIFF, BMP.
Each photo must be smaller than 1MB.
Each photo must be bigger than 256 x 256 pixels, but under 1024 x 1024 pixels.
However once you are upgraded to the new dash it might be different or if you upgrade/merge with a G+ Business it may be a little different again there too.