Have you checked and installed any system updates for your Prime, if not best to do this.
Also check the Play Store for updates to the Web storage app, there have been plenty of updates over the last few weeks. I have one penning for it atm, but do not use it. If you don't see any updates it might mean you don't have the latest updates for your Prime as the pre-installed apps did not get seen by the Play Store until the .15 update (iirc)