Thanks so much. It was grouping them all by market, just that group header was choking. A fix that worked was doing the calculation at the data level in t-sql and not in the group header, although other columns were behaving fine with expressions in the group headers.

SELECT *, ISNULL(RAFScoreDataRap,0) * 900 AS RAFScoreDataRapCalc FROM @rptMatrixMetrics

SO now this above select at the end of the t-sql script in the SSRS data tab now multiplies by 900 at this level so in the layout just needs the new column alias we created above: RAFScoreDataRapCalc

Thanks