I have been sending twits via my cellphone today and none of them have posted anybody know why?

Mine is doing the same thing. But it hasn't been just today - it's been for a few days. It has worked, but stopped working a few days ago. I can send them, but it won't show up. I can RECEIVE tweets from other people, giving me their updates, but it won't let me update my own... I tried deleting it and starting over, but I texted the code and it hasn't responded. :( What do we do?