The forwarding example you are using is incorrect or the sequence is wrong. If you are forwarding from the owner of the PhDN, you would press the phantom DN key and enter #6011 (all forward), or #6031 (call forward Delay). In your example of #6031 (no Answer), it would be #6031 9+destination + # + delay (2 digits).
For Forward all from the PhDN owner phone it would be #6011 9 + destination + #

If you are trying to set CF-ALL from another phone you would dial #6012 {Ext} # + 9 + number + #

FYI, in the past I have been able to get this working using a MCG instead of a PhDN. I have a church that is using pre-programmed speed dial keys to change the forwarding of MCG pilot number to change the on call person.