Error Loading Data

I experienced the "Error Loading Data" message also and the app wouldnt work for me. But after I rebooted my phone, that error message went away and the app started working.
In terms of the usefulness of the app, I agree with the reviewer who said that the app isnt that helpful because it only gives you the current UV status and doesnt give you the UV forecast for the day. If youre viewing the app at 6am, it doesnt tell you what the UV exposure throughout the day will be, so it really isnt useful with helping you to plan your day.

PurplePenguin007 about Ultraviolet ~ UV Index