I can't send a picture attachment together with a text message any more ( Samsung Galaxy S). Any idea why?
In case this helps someone with the same problem, I have the solution :

I had to check the Settings - Wireless and network - Mobile network - Use packet data check box. When this was done, I could send picture MMS messages.

Maybe obvious for some .. but it sure was one setting I thought I should not need just to send an MMS message.