I wrote the Complete Guide to Vampires. The Base Attack Bonus +7 and Saves: Ref +6 requirements should be dropped entirely.
On my first draft of the book I gave the vampire races Attack Bonuses and Save Bonuses. As I recall the standard vampire would have had a fighter base attack bonus and a good Reflex save. This would have allowed an 8th level standard vampire to qualify for Arch-Vampire quite easily.
However I revised the book to better mesh with the core vampire, which does not get attack or save bonuses for the levels spent in vampire and removed them. The requirements should have been removed from the prestige class but I overlooked it.
I've suggested to Joseph Goodman that this should be added as official errata for the book.
Thanks for pointing out the problem!
There is no errata for the Complete Guide to Vampires. Until this problem I had not heard about any problems with the book. If you have any other questions or concerns about the book, please ask.
There is a web enhancement for the book. This contains two NPC vampires I wrote up that were not included in the final product. You can find the download at (http://www.goodman-games.com/downloads/ ... Extras.pdf