Problems with subquery

Hi Experts,

I am new to SAP B1 and SQL so I need your help in this query.

declare @ArtGr nvarchar(max)

set @ArtGr =/* T0.ItmsGrpCod */'[%0]'

Select Case @ArtGr WHEN '102'

THEN( SELECT T0.[ItemCode], T0.[ItemName],T0.[ItmsGrpCod],  T0.[U_cpOriginal]

FROM OITM T0 WHERE T0.[ItmsGrpCod] = @ArtGr and T0.[validfor] = 'Y' and T0.[QryGroup5] = 'N' and T0.[U_Tempo] IS NULL )

WHEN '104'

THEN( SELECT T0.[ItemCode], T0.[ItemName],T0.[ItmsGrpCod],  T0.[U_cpOriginal]

FROM OITM T0 WHERE T0.[ItmsGrpCod] = @ArtGr and T0.[validfor] = 'Y' and T0.[QryGroup5] = 'N' and T0.[U_Tempo] IS NULL )

End

The error log shows me the following message: Only one Expression can specified in the select list ...

Can somebody help me ?

Thanks in advance