If you mean that the Charter remote doesn't blink twice after you enter in 20533, either 1) the entry procedure was wrong, 2) the remote has setup code lock enabled for the device button you're trying to program, or 3) the remote is broken.

Regarding 2) setup code lock, this is typical on cable remotes, but it is usually invoked only on the cable device button. However, many cable remotes have the capability to lock setup codes on other device buttons. Try using the 982 command (page 17 of the manual) to unlock the setup code for the DVD button. Press DVD instead of CBL before performing the 982 procedure.