I am sorry to tell you that GarageSale Touch for iOS has been discontinued several months ago.
It’s not compliant to newer eBay policies and changes. No matter what image service you select, uploads to eBay won’t work any longer.
If you have a Mac, you might want to switch to GarageSale for Mac: http://www.iwascoding.com/GarageSale/
It’s compliant to all eBay policies and changes.