SQL Statement Containing Multiple Subqueries for a Single Result Not Working

I'm back looking for help with another query.  I've attached a sample MS Access database containing Query1.  I'm trying to do something I've never tried before, and I don't know how to make it work.  Here's the query:

SELECT IS1.receipt_no,
        IS1.transmittal_no,
        CY.campaign_year,
        EXISTS(SELECT IS2.receipt_no FROM InspectionStickers AS IS2 WHERE IS2.receipt_no = IS1.receipt_no AND IS2.fk_inspection_type = 1) AS AI,
        EXISTS(SELECT IS2.receipt_no FROM InspectionStickers AS IS2 WHERE IS2.receipt_no = IS1.receipt_no AND IS2.fk_inspection_type = 3) AS AO,
        EXISTS(SELECT IS2.receipt_no FROM InspectionStickers AS IS2 WHERE IS2.receipt_no = IS1.receipt_no AND IS2.fk_inspection_type = 2) AS SI,
        EXISTS(SELECT IS2.receipt_no FROM InspectionStickers AS IS2 WHERE IS2.receipt_no = IS1.receipt_no AND IS2.fk_inspection_type = 4) AS IM,
        IIF((SELECT IS2.receipt_no FROM InspectionStickers AS IS2 WHERE IS2.receipt_no = IS1.receipt_no AND IS2.status <> 'U') = Null, 'Used', IIF((SELECT IS2.receipt_no FROM InspectionStickers AS IS2 WHERE IS2.receipt_no = IS1.receipt_no AND IS2.status <> 'N') = Null, 'New', 'Current')) AS status 
FROM   InspectionStickers AS IS1 
INNER JOIN CampaignYear AS CY ON IS1.fk_campaign_year = CY.pk_campaign_year 
GROUP BY
        IS1.receipt_no,
        IS1.transmittal_no,
        CY.campaign_year 
ORDER BY 1 DESC

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My problem is with the last column I'm trying to return, which I can only conceptualize as requiring nested IIF statements containing subqueries.  The error I'm getting is 'At most one record can be returned by this subquery.  My objective is to return 'New' if all rows for a given receipt_no are in status 'N', 'Used' if all rows for a given receipt_no are in status 'U', otherwise 'Current'.  Any help would be greatly appreciated.