Visual Basic.NET - recuperacion de variable de salida de un procedimiento

SET ANSI_NULLS ON

GO

SET QUOTED_IDENTIFIER ON

GO

ALTER proc [dbo].[suma_importe]

@nro_ped as int,

@vimporte as decimal(8,2) output

as

select  sum(precio_tot) from pedidos as Vimporte where nro_ped=@nro_ped

return @vimporte

Private Sub actualiza()

dim ximpte as decimal

        Try

            Dim func As New Fpedidos

          ximpte=  func.sumaImporte()

        Catch ex As Exception

            MsgBox(ex.Message)

        End Try

    End Sub

Public Sub sumaImporte()

        Dim vimporte As Decimal

        vimporte = 0

        Try

            conectado()

            cmd = New SqlCommand("suma_importe")

            cmd.CommandType = CommandType.StoredProcedure

            cmd.Connection = cnn

            cmd.Parameters.Add("@nro_ped", SqlDbType.NVarChar, 50).Value = FrmPedidos.txtNro.Text

            cmd.Parameters.AddWithValue("@vImporte", vimporte)

            If cmd.ExecuteNonQuery Then

                'Return vimporte

            Else

                ' Return False

            End If

        Catch ex As Exception

            MsgBox(ex.Message)

            'Return False

        End Try

    End Sub

Public Sub sumaImporte()

        Dim vimporte As Decimal

        vimporte = 0

        Try

            conectado()

            cmd = New SqlCommand("suma_importe")

            cmd.CommandType = CommandType.StoredProcedure

            cmd.Connection = cnn

            cmd.Paramters.Add("@vImporte",SQLDbType.Decimal).Direction=ParameterDirecion.Output

            cmd.Parameters.Add("@nro_ped", SqlDbType.NVarChar, 50).Value = FrmPedidos.txtNro.Text

            dim Correcto as integer=cmd.ExecuteNonQuery

            if Correcto=0 then

                   'Aqui código para ver si algo falló puede ser un mensaje, ya que lo tienes todo en un formulario

            end if

          dim mImporte as Object

          mImporte=cmd.Paramerters(0).Value

          if  not Isnothing(mImporte) then

               vimporte=Convert.ToDecimal(mImporte)

          end if

          return vImporte

        Catch ex As Exception

            MsgBox(ex.Message)

        End Try

    End Sub

Public Function sumaImporte()

        Dim vimporte As Decimal

        vimporte = 0.0

        Try

            conectado()

            cmd = New SqlCommand("suma_importe")

            cmd.CommandType = CommandType.StoredProcedure

            cmd.Connection = cnn

            cmd.Parameters.Add("@nro_ped", SqlDbType.NVarChar, 50).Value = FrmPedidos.txtNro.Text

            cmd.Parameters.AddWithValue("@vImporte", vimporte)

            cmd.Parameters("@vImporte").Direction = ParameterDirection.Output

            cmd.ExecuteScalar()

            vimporte = cmd.Parameters("@vimporte").Value

            Return vimporte

        Catch ex As Exception

            MsgBox(ex.Message)

            Return False

        Finally

            desconectado()

        End Try

    End Function

End Class