Question about running a carfax report on an rv.

I'm a manager in a GM dealership and we traded for a 4 year old Dodge Truck that had a major accident 2 years prior too us trading for it and it had been in accident to the tune of over $15,000 and car fax nor auto check showed it when we checked it. It was a fluke the way we found out about it. It went straight to the auction after we found that out. There are a lot of omissions on both of those reports.