Can no longer submit posts from iPhone

I am using Ember for the iPhone and have been very satisfied to date. However, recently I have been unable to do any posts from Ember. The iPhone updates posts from others, but every time I try to send a message, I get an error that says the message could not be sent and to "tap" to try again. I have tried uninstalling and reinstalling and I still have the same error. I have not made any changes to iPhone settings. Can you please help?