lost channels

I have a problem which i haven't seen before, when i scan 13e i pick up nothing until i hit 40% and
then get 11 channels and that's it but on doing a blind scan get a lot more but only about 50% of
what is available. Has anyone came across this before and what is the solution please.

Thanks Ten, i will try a different channel list first later,i was thinking maybe that was my problem.