Depends on lots of things - need more data, but I can offer this.
Sounds like you have your shore line plugged into the 240v mains and you're expecting your lead acid house battery (caravan battery) to be charged by that. Also, you're thinking the engine battery should also be charged.
Neither of these are necessarily the case.
In my own rig - a Winnebago Via model R 2012 - there is a 2-stage built-in battery charger that will charge the "house" (caravan) batteries when you're plugged into the mains (115V here in the US).
Now, if that charger were defective, the mains would power the caravan outlets with 115V, but the 12V service to the lighting & other devices would be faulty. Are you still getting 12V DC to other devices in the rig?
In my rig, the shore line power ONLY charges the caravan batteries as wired by the manufacturer. What I did was to install something called a Trik-L-Start between the caravan batteries and the engine battery. This allows the caravan battery charger to also charge the engine battery when it's plugged in (as long as the caravan batteries are alive).
In my rig, if the engine battery goes dead, you can press a switch and start the engine from the house batteries - so all you need is one battery to be good.
But that's a long answer to your question - and the short of it is that for one reason or another you either do not have a battery charger in your rig, or the battery charger is itself dead.
There are ways you can test for that if you're interested I can help.
Cheers
Joe