My female roborovski hamster won't let me pick her up or even pet her. Why?

i have had my first female roborovski hamster, Otie, since April 10th 2011 but she still won't let me pet her or pick her up. whenever i try to pet her she seems skittish and runs all over the cage. When i try to pick her up, she just slips out of my hand. after i chose my hamster, the guy at petco took her out and let me pet her but i didnt hold her. we brought her home and i gave her time to adjust to her surroundings. a few days later i tried petting her again but she ran all over the cage. I thought that she needed more time to just get used to her new home, but then i tried to pet her again, again with no luck. now, whenever i put my hand in the cage so she can hopefully crawl into my hand she bites me or hides in her hut. will she always be like this? maybe because she is the only hamster in the cage and she may be getting lonely?