Maybe I'm missing something obvious here... but it seems that if I send a text message to someone, and then leave the window with the threaded conversation with that person open, when they reply the blue LED light does not go on like it usually does when an SMS comes in. I keep missing people's messages because of this!

It's not helped by the fact that it doesn't make the usual 'SMS recieved' sound either - just a little click which is really easy to miss.

Is there any way of changing this?