[Zubersoft]

That seems to indicate you are loading MobileSheetsPro by tapping on a file using another app and it can't load that file. Is that the case? The weird part is that it says the file name is just "/", which doesn't make sense. Had you previously loaded a file that way into the app, then switched to another app, then reloaded MobileSheetsPro by tapping on the icon without closing the previous instance?