Question : Cant display related column values in result set...

What I am trying to do is to display the alias field in a related table.  the code runs but the chem column is null...it is not finding the alias value to display.  

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER Procedure [dbo].[spLocal_NWW_Select_OOSpec_Data_LastHour]

              
AS  
DECLARE @ChemName nvarchar(255)
SELECT @ChemName =  Alias From [Tags] Where [Tag] = @ChemName  
SELECT
       @ChemName as Chemical
      ,[ValidTime]as Hourly_Reading
      ,[ActualValue]
        ,[DesiredValue]
      ,[Reason1]as Evaluation
      ,[Reason2]as Reason
      ,[Reason3]as Course_of_Action
      ,[Reason4] as APM_Response
      ,[Comments]
      ,[ValidOPId]as Operator_Signature
      ,[ValidAPMId]as APM_Signature
      ,[ValidPMId]as PM_Signature
      ,[OOSpecFlag]as Out_of_Spec
        ,[SiteCode]
        
FROM [CWD_Operations_Reporting].[dbo].[ValidationDetail]

WHERE ValidTime >dateadd(hh,-1,getdate())
and OOSpecFlag = 1
and SiteCode = 'NWW'

 

Return

Answer : Cant display related column values in result set...

ok, let's start here:

SELECT @ChemName =  Alias From [Tags] Where [Tag] = @ChemName  

where does @ChemName, for the WHERE part, come from?