You probably wiped out the selector codes when you re-recorded your auto attendant greeting. If your extensions are in the 10-19 range, selector code 1 should be set to Direct Extension Transfer, so that when the caller presses the first digit (1), the system knows to wait for the 2nd digit and transfer to the 2 digit extension. Same thing if you have extensions in the 20-29 range, selector code 2 should be set to direct extension transfer.
Log into the System Administrator's mailbox, select the auto attendant, select the day menu, modify it, press 1 for selector code 1, and if you don't hear that it is set to Direct Extension Transfer, select the option to make it do, then *# to quit selector codes, and # to keep the current recording.