Trying to create a formula field in report for Forecast Category, keep on getting Syntax Error Found "." Help required please :-)

IF(ForecastingItem.ForecastCategoryName="Closed", 1*ForecastingFact_Opp.Amount:SUM,IF(ForecastingItem.ForecastCategoryName="Commit",.7*ForecastingFact_Opp.Amount:SUM,IF(ForecastingItem.ForecastCategoryName="Best Case",.5*ForecastingFact_Opp.Amount:SUM,IF(ForecastingItem.ForecastCategoryName="Pipeline",.075*ForecastingFact_Opp.Amount:SUM))))