Vectra : Driver's Door Wont UnLock !?

This evening I got out of the driver's door, but couldn't get back in a few mins later! The door will not unlock either by using the key fob to zap or by the old fashioned way of key in lock! Further investigation seems to reveal that either way, when I lock it, there is only the whirr of the doors locking & not the 2nd whirr of the Deadlocks(?)! Any ideas? (I'm left getting in & out via pax doors!)