Maci cried, and cried, and cried the first 3 or 4 days that we had her at our home. They just get so worked up because of the new environment, and they miss their past home.
We basically just ignored it (after many sleepless nights) and she has turned out great! We did leave a little nightlight on for her next to her crate, and we did have a small radio going as well (playing talk radio). It seemed to calm her a bit, but never did completely stop the crying for those first few nights.
She now doesn't require anything at night, and she'll sleep a good 8-9hrs before she'll cry letting us know she needs to go potty.
Just hang in there, it will get better!