I think your daughter misses her friends at the old school and the known surroundings. She should have been settled by now but some kids need more time than others. I don't think there is any reason to worry.

yuktimaan, Sunita might be right. But I will suggest that you talk to parents of some of your daughter's classmates to confirm all is well at the school. You can also talk to her classmates to know their opinion on the school.
Hope this helps!

he can have other type of fears.

speak to him to find out if he has any concern. maybe some teacher did not treat him well and now he is either scared or doesn't like spending time with the teacher.

can he communicate about his feelings. doesn't matter the words. but try to sense if he behaves like this due to discomfort with some environmental factors at his school.

I know this discussion is an old one. But still want to give my input on this. I went through a similar situation with my daughter. Actually few months back I changed her school and she had similar behavior.
What I did was went to school and talk to some of her classmates and came to know that one day she did drop her tiffin in school by by mistake and on this her teacher scolded her. This is what she did not like as the teachers in old school used to love her. I met the teacher and asked her to be good to my daughter. Next day when my daughter went to school the teacher apologized to her and slowly my daughter has adjusted.

yuktimaan I hope your daughter is settled by now if not please try to meet her teachers and classmates you will definitely get some clue.