Research differs significantly from the private industry, and punishing scholars whose data base is still incomplete, too coarse-grained, inconclusive or outrightly negative is a really, really bad idea. The problem is that negative or inconclusive results never get published in peer reviewed journals. You can tell your colleagues about this over a drink in a bar, but that doesn't count as publication. No major archaeological journal will ever publish a paper in which the authors say: "Oh, we tried this-and-that in region X, we have employed every available technique over the course of so many years, we have spent tons of money on that - and we found nothing"!

Of course, this piece of information would be extremly important to the three or four of your closest colleagues - on the one hand, it prevents them to do the same mistake, and on the other hand, the very lack of evidence may in itself be evidence for - well, something. Maybe something else, which no-one has ever thought of before.

"We found nothing" will not, however, impress the wider academic world - the interested public, publishers, funding agencies, the dean of your faculty. But this is a problem of academic culture, and individual researchers should not be punished for that.