It is the activator has not being updated yet. Even if you can downgrade the firmware, you cannot downgrade the ipad baseband, it will remain as it is.
I suggest you restore again to custom firmware of 4.2.1 to test it it out
OR if there is a newer version, you can ssh into it and add the .deb file to Cydia/autoinstall. I am not sure if there is any never version yet as i will be at 4.1 for awhile, there is no neccessity for me to upgrade to 4.2.1.
Last edited by iYeow; 12-27-2010 at 08:23 PM.
Reason: Automerged Doublepost