2004 jeep grand cherokee 2.7 crd - 2004 jeep grand cherokee gearbox problem - melvyn

i have a 2004 jeep grand cherokee 2.7 crd with an annoying problem the gear box itself is working as it should but when i park up it wont allow me to put it in park straight from drive i have to pull the gear lever back into reverse or drive and then it will go into park has any body any ideas what could be causing this? the car has only done 56000 miles