my daughter wont talk in daycare

Hi,my daughter is 3 years old,she is very outgoing and playful and does talk a lot. But around other people she is shy which I understand as that's her personality,it takes her awhile to play with kids.even friends of mine that have children the same age it took her awhile but now she does talk and play with them.my problem is at daycare.she has been going to daycare for the past 11mnths,and they are fantastic teachers as they are trying to help my daughter to get confidence and open up.but she won't? She hasn't said a word since day one going there,and won't play with other children,she interacts when they are inside when they are painting or drawing but as a social thing she won't join in,.when they are singing and doing dance movents she will just stand around and when they play outside she just stands in one spot and watches but won't play.if another child tries to play or talk to her my daughter looks away,but when a teacher comes up to her and says lets go for a walk she will hold the teachers hand and follow her.I'm confused on what to do as at home she is a bubly child,plays and talks a lot! I try to encourage her and tell her to have fun and play with other chidren but she won't.she stills crys when I drop her off at daycare but they keep her occupied during the day with activities,I'm worried that she will always be like this and won't talk if she isn't well or needs help,I'm worried for when she does go to big school if she will be like this and not like the other children who run off and play.is there a way I can help my daughter and is this common