Being a relative newcomer to the world of smartphones, I am slightly baffled by a failed attempt to send a text message, which resulted in the legend 'Cannot Send.'

This was the same using two Android phones, both SE Xperia X8 models, to a Blackberry. Text to other phones seems to work fine, and my girlfriend and I - owners of the SE models - can receive from the Blackberry in question.

Anyone got a clue as to what is going on?

Are you putting a subject line in so it is treating it as an email rather than as text?

No, we're doing nothing different than we do with any other text message. Number has been triple checked, and is fine. Exactly as shown in messages from the Blackberry owner. Strange.

How disappointing that the massed brains of DS cannot fathom this small mystery.