Firstly Go into the services menu and check the signal strength and quality, if this is OK, try switching of at the mains and then back on again. If this doesn't work and you are connected to a phone line do a new installation. Go in to Services/.System Setup/0,1,Select/New installation, it is probably that the software cannot find the newly moved channel.
This will then rescan all of the channels.
If none of this works then a forced update may be necessary.