One common reason for your Keypad EZ to stay unlocked is that is has been inadvertently placed into passage mode.
To verify if you are in passage mode or not you can do the following:
Enter 00# followed by your admin code and a # (sometimes this code is the code you open the door with.
It is advised to change that admin code and make the old code a user code (in lieu leaving it as admin). This will keep your door from becoming unlocked for extended periods of time in the future.
To change your admin code and program the old code as a user code do the following:
Keypad EZ, 9KZ, 45HZ