ExpertDesigner cost differences

Why would my printed report show a lower cost than the design assistant for a span?
I have 20,000 feet of pipe (with a few other minor items) with a total material and labor cost of $178,254.40

The Cost Estimate report shows $163,717

This is a single span of pipe. I did place this again in 2 different spans and the cost differential is the same.

Any hints would be appreciated.

Expertdesigner V8i SS1