Twitter mobile with Samsung Instinct problem

I use a Samsung Instinct (m800) phone on Sprint service. I used to go to the Twitter mobile site and enter updates from there with my treo 755p fine but now i have the instinct. This worked 2 times with the instinct but now it gives me an error & will not accept my updates this way.
The error pages says "Sorry, you can't access this in the way you've tried." i've tried playing around with all the settings on my browser and clearing the cache nothing works. It just seems to work at random times.