Where are you pricing it from??

The MPM (max permitted mileage) for the LH fares was very very low: I looked at PHX-FRA-MAN, and the fare allows up to 6298 one way.... the distance PHX-FRA-MAN is 5636+517=6153.

If you're trying to price from, say, SFO, any connection other than one in FRA may push it over the allowance.