Radio Programme Not in Cache

[Budge]

Hi all and sorry if this has all been explained before.  I wanted to 
record "The Book of Dust" so refreshed my cache by running get_iplayer 
thinking I would find the index number and get it as usual but the title 
does not appear.

I therefore downloaded it using pid but can somebody explain why the 
title does not show in cache.  Is it because it is just too soon, the 
programme was only broadcast yesterday, or something more sinister?

Budge