My hamster is very friendly but why does she do thiss...?

my cambles ? dwarf hamster is very friendly, she crawls on me, and likes to be played with and all, but when it comes to pickinq her up in her cage or pickinq her up when shes on my lap, (it doesnt really matter where) she gets scared and and runs away, or she trys to bite me when i qo to pick her up; is there any way to try and train her, or do you know what the prob is ? and no shes not pregnant, she is the only hamster i have