Help! APN not saving!!


I upgraded my ace to Android 2.3.3 and since have been facing problem of APN not being saved. I try making new APNs and save it. And it gets saved. but if i change the MNC value it vanishes from the list.
The default MNC value is set to 03. I need it to be 039. but if it change it from 03 to 039 it just wont save.:(
Pleas help!