Using Outlook on kindle fire hd: nothing in Trash and Sent folders… how to fix?

I'm using Outlook on the kindle fire hd (got Outlook from the kindle app site). Works great except that the Sent, Trash and other folders are always empty. I've tried the suggested fix of deleting Outlook from the kindle, and re-installing it. This sometimes works, but usually doesn't. When it does work, it's only temporary... eventually these folders become empty again. There must be a permanent fix for this... anyone? thanks!