Make sure you are using Xolox V1.12 and the hostslist.txt (fresh downloaded) looks like this (only 3 lines posted):

I;2;>8;2:6346
KI>2;2>8:6347
2?L:;3>;:6346
...

If you don't see some numbers at the end of each line, it's a old hostslist.txt which will NOT work with Xolox V1.12. More details here.