Today on our way to GFK, we overhear a Pinnacle crew looking for a place to divert because of the weather in MSP. A requirement for their diversionary airport was if they had Type IV anti-ice fluid. They finally felt comfortable diverting all the way to GRB, because it was the only station that had Type IV in stock in August!!!! Someone in the Pinnacle training department needs to step and start teaching certain Pinnacle crews that Type IV fluid does not keep ice off the aircraft while enroute.