Inconsistent use of past sale data on same home.

How can Zillow say my home has lost value since it's last sale, but also say it doesn't use that sale price in the Zestimate.

For example, my Zestimate in high 5's. We bough the house for mid 4's and in the statistic area Zillow says the home has lost ~5% since the last sale, which lists the date of the sale Zillow says it is not including.

There is a sale a year prior to our purchase that I agree should not be included because it was a foreclosure but I believe our purchase should be included.

Is there a way to get Zillow to correct this?