I can't recode the central locking

[Titan]

I'm trying to recode the central locking module on a 2002 model.
The current code is 15179 and I would like to add the following;
+00004=selective locking
and
+00032=locking via speed
When I try to change the code to 15215, I click on 'Go for it' and it takes me back to the main central locking module screen but the original code remains.
I've tried just adding 4 and then just adding 33 but to no avail.

I do have an error code for the alarm which re-appears as soon as I clear it so I wondered if you maybe cannot recode when there is a fault?

Any help would be appreciated.
Thanks.