no data captured on hopping channel

[mathblue]

Hi, I posted on stack a related question with all the details of what I'm trying to do since is not a gr-gsm bug (https://superuser.com/questions/1806719/cant-see-my-update-location-request-but-kc-has-changed-general-information-abo)

here I would like to ask:
I have just 2 hopping channels in my Arfcn list of system information type 1 but with gr_gsm_livemon I can see data only on the first one no matter what I do, maybe there's no coverage for the second frequency but it seems strange...
Is it as I had a single channel or do I have to care about the hopping anyway in the decoding phase?
The thing is that I can't see any Authentication requests on BCCH, hope my dongle is not broken...
thanks