I've to print SalesPackingSlip report and only if SalesOrder has a specific value on a custom field I've to Group by itemId, else I shouldn't Group on ITEM ID even if I've twice the same item. I've used a boolean parameter on the contract that is true only when I want to Group on itemId. To condition the grouping on this parameter I wrote in the General Group properties this expression:
iif(parameters!isEDISalesOrder.value = 'true',
Fields!ItemId.Value,Nothing)
but it doesn't work. Could you help me some way?