AA = (PortfolioSectorWeight - BenchmarkSectorWeight) * (BencharkSectorReturn - BencharkTotalReturn)

This formula makes complete sense.

Look at it this way, if you were trying to analyze whether overweighting or under-weighting a sector makes sense or not, just think... if the sector give higher return than overall benchmark then it makes sense to overweigh and vici-versa (remember benchmark total return is weighted average return of constituent sectors).

Plz feel free to ask for any clarifications.

Regards,
Sharad