custom.handset.auto_answer.enable not working

Dear,

In de Auto Provisioning Guide the setting "custom.handset.auto_answer.enable" is defined as:

"It enables or disables a user to answer incoming calls by lifting the handset from the charger cradle without having to press the off-hook key."

However, when I provision "custom.handset.auto_answer.enable = 0", afterwards, on lifting the handset from the charger, the phone still auto answers the phone.

The basestation has firmware 25.73.0.40
The handset has firmware 26.73.0.11

How should I configure this?

Thanks,
Samuël