I had the same problem with a pair of black pastels I got in August. They were started on live hopper mice and I feed F/T. Basically I solved the issue by 1)Leaving them alone for 7 day period. I only went in to change water. 2)Thawed out the mice in water and then placed them in hot water for about 5 min. and as disgusting as it sounds I cracked the skulls. 3) Did the best zombie dance ever and low and behold they took them. Sometimes we rushed to feed babies when they just need to acclimate to their new homes. I have been feeding 2 times a week and no problem. Don`t freak out just have a little patience