Tvheadend

Tv headend after importing a playlist doesnt read all the channels but selects some and blacklists them why is that? For the first time import it blacklisted about 60 chan out off 180. Now some off them started working. When i checked channels/ dir in the settings area of tvheadend and found that the chanels that dont work dont have a PID data and they contain only basic channel data IP UDP chan position but not the other. Why tvheadend wont read and write this data into chan files is a mistery and it likes to select it.

I have Ubuntu 11.04 server
Tvheadend 2.12 installed and running.