I have a mondeo 2010 titanium X which has keyless entry and start and seems to have a strange problem with the lock/alarm.

When I return to the locked car and open the boot using the handle on the boot it unlocks and opens as you would expect, but if my wife then try's to open the rear passenger side door whilst I have the boot open the door unlocks and opens but the alarm goes off.

Surely if the alarm goes off it shouldn't have allowed the door to be opened in the first place.

Any idea what could be the problem?

Thanks very much