Rechargeables are 1.2v, whereas 'normal' batteries are 1.5v.
So the 'worn out battery' detection circuit will kick in earlier.
Put the rechargeables in a torch and leave it on to drain them completely.
Recharge them and then repeat a couple of times.
This will get rid of the 'memory effect' which stops them from holding a full charge.
If you are considering buying new ones, go for NiMh (Nickel Metal Hydride) ones
which don't suffer from this problem.
Check your camera instructions, as it may say not to use rechargeables.