I have the following stored procedure which can be sorted ascending and descending on TemplateName,CreatedOn and UploadedBy. The following SP when runs doesnot sort records.if i replace 2,3,4 by columnname, i got an error message "Conversion failed when converting the nvarchar value 'Test Template' to data type int.".Please suggest how to achieve sorting.

CREATE PROCEDURE [dbo].[usp_SEL_GetRenderingTemplate]
(
  @facilityID INT,
  @sortOrder VARCHAR(5),
  @sortExpression VARCHAR(100),
  @errorCode INT OUTPUT 
)
AS 
BEGIN       
    SET NOCOUNT ON ;
    BEGIN TRY   
        SET @sortOrder = CASE @sortOrder
                           WHEN 'Ascending' THEN 'ASC'
                           WHEN 'Descending' THEN 'DESC'
                           ELSE 'ASC'
                         END
        SELECT  TemplateID,
                TemplateName,
                CreatedOn,
                ( [user].LastName + ' ' + [user].FirstName ) AS UploadedBy
        FROM    Templates
                INNER JOIN [user] ON [user].UserID = Templates.CreatedBy
        WHERE   facilityid = @facilityID
        ORDER BY CASE WHEN @sortExpression = 'TemplateName'
                           AND @sortOrder = 'ASC' THEN 2
                      WHEN @sortExpression = 'CreatedOn'
                           AND @sortOrder = 'ASC' THEN 3
                      WHEN @sortExpression = 'UploadedBy'
                           AND @sortOrder = 'ASC' THEN 4
                 END ASC,
                CASE WHEN @sortExpression = 'TemplateName'
                          AND @sortOrder = 'DESC' THEN 2
                     WHEN @sortExpression = 'CreatedOn'
                          AND @sortOrder = 'DESC' THEN 3
                     WHEN @sortExpression = 'UploadedBy'
                          AND @sortOrder = 'DESC' THEN 4
                END DESC
        SET @errorCode = 0


    END TRY
    BEGIN CATCH
        SET @errorCode = -1                            
        DECLARE @errorMsg AS VARCHAR(MAX)  
        DECLARE @utcDate AS DATETIME   
        SET @errorMsg = CAST(ERROR_MESSAGE() AS VARCHAR(MAX))  
        SET @utcDate = CAST(GETUTCDATE() AS DATETIME)  
        EXEC usp_INS_LogException 'usp_SEL_GetFacilityWorkTypeList',
            @errorMsg, @utcDate  
    END CATCH 


END