Order by in stored functions

Hello

I tried to create the following function

CREATE Function pGetMenu ( int )
returns setof varchar
As '
SELECT IdMenuShow || IdWebPage
FROM Menu
WHERE IdMenu = $1
ORDER BY IdSort ;
' language 'SQL' ;

I've got the following error message:

ERROR: function declared to return varchar returns multiple values in final retrieve

If O just remove the ORDER BY clause als works well so I guess that the
ORDER BY has to be replaced by somethjing other. Could somebody
enlighten me how to do the ordering in a stored procedure?

Kind regards

Andreas.