She isn't crying for no reason. She's only 6 weeks old and too young to be parted from her mother and littermates. Likely she's a bit scared/nervous/insecure and wondering why mommy isn't coming to her when she calls.
If you have the option, I'd take her back to be with her mother and littermates (if her littermates are even still there now) for at least another 2 weeks. If not, you'll just have to give her time to adjust. As for her name, use it a lot, and never in a negative way. She'll soon catch on.