I've played both mods in the past, but I recall being able to do the main quest in NVB I alongside some bounties from posters in NVB II. Now I installed both mods again and started a new save, but Boulder City Jail is gone and I can't start NVB II at all (though I did start NVB I). Is anything wrong or changed?

If I recall, someguy updated his mods and added the someguyseries.esm, so it allows his mods to interact with each other and all that.

It also means that NVBII won't start until you finish NVBI.

Yeah, I noticed it needs the master file now, just wasn't sure about this bit.

Thanks a bunch!