Cseries :: Send Group Messages From Nokia C7?

I am not able to send Group messages from Nokia C7.I am sending messages to a distribution list having 70 members in it, only 20 messages are going fine and the remaining 50 stuck in the inbox saying Failed or Resend at XX:XX.Then i usually try to click on each message in the out box and send them again. [i dont know why there is no mark all option in outbox ] But from 3 days eventhough i am trying to send the 50messages again it is just saying Resend at XX:XX.

1) I tried sending the messaged from OVI suite but no luck

2) With help of vodafone customer care i verified all my message settings, message center number and everything are fine. (if they are wrong the first 20 should also stuck na..)

3) I thought it was a n/w problem i called to vodafone Customer care and they asked me try in another phone.

4) I have taken my old nokia 5310 Xpress music inserted the same sim and sent the 70 messages, they all went very fine.