In the past, why were you calling them to you? Sometimes if you mainly call them to do unpleasant things, they remember and anticipate what you are going to do. I would try having treats with you and rewarding when they come to you. Once they associate a treat with answering your call, you are home free.
Also, if you look up the stages in a puppy's development, 4-8 months is when they become more independent. If they always came when called, you may see them ignoring you. There are a lot of good sites that give you training tips. Good Luck!
__________________ Kim  Mommy to my angels, Chelsey, Zoey, and Cooper |