How to help my daughters to make friends?

We moved into this neighborhood a year ago. My 7 year old and 9 year old still do not have regular friends. We've invited kids over and no one has invited my kids over. I've called and tried to make play dates for the girls but the parents haven't called back. One Mom did have my 9 year old over last year when we first got here. She told me that my 9 year old wasn't as mature as her child and didn't want to get them together again (my child still plays with dolls etc...) I called another mother last week and she didn't call back. I know my child is shy but I don't know what do do anymore. Should I just sit back and let her be friendless? We did just sign her up for dance and ice skating. It's just really heart breaking as a parent to see your kids so lonely at school. Luckily they have each other at home. Any suggestions?