It took Archie quite a while before he slept through the night, in fact I was so sleep deprived by his getting up every two hours, I felt like a new mommy of a human child! I brought him home when he was 3 months old and it was maybe two months more before he started sleeping straight through to about 5 or 6 a.m. without an accident in his crate. So, it may take some time. Even today at a year-and-a-half he will get be up at 4 a.m. to tinkle if I do not take up his water and food before 9 p.m. at night! It just takes a long time with some of them -- hang in there! 
