Colchester Zoo rail ticket

[moley-uk]

Hello,
I'm shortly going to be making a journey to colchester zoo from london, and noticed the combined ticket on national rails website, and also in the NFM, including NFM03.
I asked one of the guards on my journey if he would be able to issue them from his avantix machine so i've got the tickets in advance.
He tried doing London Liverpool street to Colchester Zoo (which came up as colchesterzoo676 on his machine) (LST - J005) but was unable to come up with a fare, yet NFM03 shows a fare for that journey.

Any ideas anyone? as the guard I was talking to was quite puzzled by this

Thanks

 

[Nick W]

http://www.nationalrail.co.uk/times_fares/promotions/pr99d3ae619f410890a9297357aa7c60/details.html
lists a limited number of stations from which it is available. Where did the guard try to issue it from?

 

[moley-uk]

The guard tried Liverpool street to Colchester Zoo, and also tried Clacton as we may be staying there over the time we want to go.

I was just seeing if I could save some time, and get them in advance from my regular guard.