Sometimes I find what helps is to add default value as a separate data item and then drag in your default expressions. Validate each data item individually first
parallelPeriod ( [great_outdoors_company].[Years].[Years].
[Quarter] , -1 , [2006/Aug] ) ...
parallelPeriod ( [great_outdoors_company].[Years].[Years].
[Quarter] , -1 , [2006/Aug] ) ...