Negative Brand Loyalty

Hi, any idea why my brand loyalty went to negative (-5 now)?

I have the Corporate Brand strategy, I have 3 product lines (auto, computers and communications), and almost every product have the best technology in the market, and my total score is usually 3 points higher than the market avg. I have warehouse in the middle of factories and retail stores, so usually there is no supply disruptions.

I have both my headquarter and one retail store doing marketing, each spending $500K per month.

The brand loyalty used to be pretty high, but suddently I saw it became negative.

I got confused, what I did wrong that caused it?