Xbee Serie2 strange behaviour in sleep mode hibernate sm=1

Hi, I set up a zigbee network with one end device and one coordinator. I set my end device in sm=1 since i want to send rf data to my coordinator only when DTR goes to ground (opened door event). I correctly receive data when this event occurs but also I see that my coordinator receives data periodically (saying once a minute about 7 rf data) with no reason! Why this happens? Why I get rf data not only when DTR goes to ground ?This is not Pin hibernate behaviour I want! Is there some reason related with SP SN Parameters in my Network? Is there a firmware version problem or something else! Please, an help will be apprecieted!
Thanks in advance! Nico

On which pin are you providing this input, it should on pin 9.

Also check, if voltage level of your input is sufficient enough that module can detect it. It should be continuous and just not a pulse.