It sounds like she isn't ready. I was going to suggest you hanging around for 30-60 minutes then leaving, but you've already tried that. It's hard for the little ones when they're only going 1 day a week as it takes a long time for them to adjust.
If she was crying only when you initially left, then I would suggest you giving it a few weeks to see how things go, but if she's crying all, or most of the day, then I would pull her out.