Nokia 6233: Yahoo Messenger Predictive Text

I recieved my new Nokia 6233 today, I'm very happy with it except one problem. I use the GPRS version of Yahoo Messenger pretty much all the time, but this phone will not let me use predictive text when I'm sending messages on Yahoo whatever I try. I've never had this problem with any other phone before, so have I missed something or am I gonna have to change the phone for something different?

Thanks