Take the gate down. It tells her that she is locked in her room and that she can't get to mommy if she needs too. Put her in bed, tell her to stay there. If she gets up, put her back no matter how man times it takes. If she stays there but still cries, come and check on her in 5 minutes, then leave...still crying extend the time out to 10 minutes. Increase the time by 5 minutes each time. This lets her know that mommy will come if she really needs you.
Is this the first time she has been in a room by herself? If so, you may need to stay in there with her the first few nights. What I did, sit in the rocker next to the bed and read a book (to myself not out loud)until she's asleep for the first 2 nights, then each night after that, move the rocker closer to the door. The night that you leave the room you will need to do the above of letting her CIO for 5 min, then 10 and so on. It only took 7-8 days and she was fine
at 10:35 PM on Jun. 19, 2010