Ok I read in here that some developers are having problems making and using lockable doors... So I will explain how to make one. The example I will show is a lockable door that opens with a key that the player picks up in level.
Once you place your key, make sure to remember the name of the key ( by default the key\'s name is whatever enitites name is like key1 or key2, and so on.)
Next right click on the door and make sure the settings are like below.
The image below shows the key settings and door settings.
** They are labeled**
Hope This Helped,
EWEST