>I'm trying to create an average on a report group.

It seems like I dealt with a similar item this way: for the Average Field in the report group footer, in the 'Report Expression,' in the 'Print When,' in the 'Print only when expression is true:' put an expression like

FirstCast = .F.

You also select Average in the Calculations, along with making sure its on the group.

Mel Cummings