The previous events in iOS5 can reach back one year on your device at most, events before that are only visible on your computer. Did you make sure, that "don't sync events older than...days" is not checked in your info pane/calendar section in iTunes?
IT says "No supported calendar applications can be found" I never had this problem before I upgraded the software to ios5. I just have the Iphone 4 and just upgraded the software. Perhaps it's a bit buggy?