My Dwarf hamster wont let me pick her up?

Every time i ry to pick her up, she scurries away realllly fast. I can scooper her up, but then she eventually jumps out of my hands. She seriously will NOT let me grab her (gently of course). she will only let me scoop her up with her little igloo home. she just runs away from me every time. i got her 3 days ago. I have tried putting a treat in my hand, but she wont take it. just sniff and leave. What can i do to make her let me grab her?