MV-8000 HELP!!!!!

[ghostserver]

hi guys i got the mv about a month and a half ago and am have trouble with just a few things i still need to get the kinks out so heres my question how would i go about creating the perfect loop from a sample i have edited what i mean is it will be sliced perfectly and bpm sysc well but when i try to copy and paste it it statrs throwing my beats off if anyone can help me it would be great thanks