Using a stored procedure with output parameters in a gridview

He there:

I have a stored procedure that has some input parameters and some output parameters. The input parameters are supposed to be drawn from two user controls (hiddenfields) and one is supposed to be taken from the querystring. The output parameters are supposed to be viewed in the detailsview that displays my data.

However I have no luck doing this. It seems as if I cannot display the output parameters as rows in my gridview, and it seems I have to give my output parameters a value before the stored procedure is executed - which is pointless, because this is not relevant.

Any ideas?

The stored procedure looks like this:
ALTER PROCEDURE dbo.ejNotifiedTilmeldinger

            @antal int OUTPUT,
            @not_notified bit output,
            @dato varchar(30),
            @kursus_id int,
            @profil_id int

AS
      declare @antal2 int
      
      SET @antal=0
      set @antal2=0
      set @not_notified='false'
      
      select @antal = count(*)
      from kursusTilmelding
      WHERE kursusTilmelding.dato = @dato
      AND        kursusTilmelding.kursus_id=@kursus_id
      AND        kursusTilmelding.profil_id = @profil_id
      AND        kursusTilmelding.slettet = 'false'
      and   kursusTilmelding.notified = 'false'
      
      select @antal2 = count(*)
      FROM  undertilmeldingNy
      WHERE undertilmeldingNy.dato = @dato
      AND        undertilmeldingNy.kursus_id = @kursus_id
      AND   undertilmeldingNy.slettet = 'false'
      AND        undertilmeldingNy.betalingsprofil_id = @profil_id
      and   undertilmeldingNy.notified = 'false'
            
      set @antal=@antal+@antal2
      if @antal>0 set @not_notified='true'

RETURN @antal