issues with subquery sql
used:
WITH sub AS (
    SELECT 
        t1.itemcode as sapitemcode, 
        t1.CodeBars as Barcode, 
        t1.ItemName as description, 
        LEFT(t1.ItemName,20) as short_description,
        --MAX(case when T0.PriceList = 1 then t0.Price else null end) as price_1,  
        case when T0.PriceList = 1 then t0.Price else null end as price_1,  
        NULL as precio_tableta,
        CASE t0.PriceList when '1' THEN 1 END as Price_level_1, 
        --CASE t1.SalUnitMsr when 'PZA' THEN 1 WHEN 'UND' THEN 1 when 'CAJA' THEN 1 when '' THEN NULL END as uom_group_id,
        case when t1.NumInSale &gt; 1 THEN '1' END as uom_group_id,
        (   SELECT T5.[ItemCode]
            FROM AITM T5 inner join OUSR T6 on t5.usersign = t6.internal_K
            WHERE T5.[ItemCode] = 'CID-11418272385'
            group by T5.[ItemCode], T6.[U_NAME], t5.loginstanc, t5.updatedate
            having t5.loginstanc = (select min(loginstanc) 
                        from AITM 
                        where itemcode = 'CID-11418272385')) AS col1,
        (   SELECT T6.[U_NAME] as 'User that created Item'
            FROM AITM T5 inner join OUSR T6 on t5.usersign = t6.internal_K
            WHERE T5.[ItemCode] = 'CID-11418272385'
            group by T5.[ItemCode], T6.[U_NAME], t5.loginstanc, t5.updatedate
            having t5.loginstanc = (select min(loginstanc) 
                        from AITM 
                        where itemcode = 'CID-11418272385')) aS col2,
        (   SELECT t5.updatedate
            FROM AITM T5 inner join OUSR T6 on t5.usersign = t6.internal_K
            WHERE T5.[ItemCode] = 'CID-11418272385'
            group by T5.[ItemCode], T6.[U_NAME], t5.loginstanc, t5.updatedate
            having t5.loginstanc = (select min(loginstanc) 
                        from AITM 
                        where itemcode = 'CID-11418272385')) AS col3,
        CASE t1.VatGourpSa when 'V0' THEN 4 when 'V1' THEN 1 WHEN 'V2' THEN 2 WHEN 'V3' THEN 3 END as Impuesto, 
        t1.U_GRUPOA as Grupo, 
        t1.U_GRUPOB as Departamento, 
        t1.U_GRUPOC as Categoria, 
        t1.NumInSale as ItemsPerSalesUnit, 
        t1.SellItem as SellItem 
    from ITM1 T0
    inner join oitm t1 on t0.itemcode = t1.itemcode
    inner join ouom t2 on t2.uomentry = t0.uomentry  
    where t1.ItemCode='CID-11418386891' 
    and PriceList='1'
)
SELECT sub.sapitemcode, 
    sub.Barcode, 
    sub.description, 
    sub.short_description,
    MAX(sub.price_1),  
    sub.precio_tableta,
    sub.Price_level_1, 
    sub.uom_group_id,
    sub.col1,
    sub.col2,
    sub.col3,
    sub.Impuesto, 
    sub.Grupo, 
    sub.Departamento, 
    sub.Categoria, 
    sub.ItemsPerSalesUnit, 
    sub.SellItem 
FROM sub
GROUP BY sub.Barcode, 
    sub.description, 
    sub.short_description,
    sub.precio_tableta,
    sub.Price_level_1, 
    sub.uom_group_id,
    sub.col1,
    sub.col2,
    sub.col3,
    sub.Impuesto, 
    sub.Grupo, 
    sub.Departamento, 
    sub.Categoria, 
    sub.ItemsPerSalesUnit, 
    sub.SellItem