Oh well, its the only tracker that can be used with vBulletin software, its good tho
Anyways, about your error. You'll have to import an .xml file, right? It itself is big and it carries out very big DB operations. Well, it takes time on slow servers and may be sometime timeouts occur.

What I suggest is just drop all the tables related to vBitty and try re-importing the .xml and it should be fine.
And before all make sure you've editted the config file on vBitty (forgot the name ). The DB used with vBitty should be the same you used for vBuletin as it creates ratios, etc.


Regards.