Visual Basic.NET - referencia a objeto no establecida como instancia de un objeto

Private Sub printPreviewButton_Click(ByVal sender As Object, _

	ByVal e As EventArgs) Handles printPreviewButton.Click

	Dim connetionString As String = Nothing

	Dim connection As SqlConnection

	Dim command As SqlCommand

	Dim adapter As New SqlDataAdapter()

	Dim sql As String = Nothing

	connetionString = "Data Source=Josep-Pc\sqlexpress;Initial Catalog=Desplacaments;Integrated Security=SSPI;"

	Sql = "select id, data, idorigen, iddesti, km from Viatge"

	connection = New SqlConnection(connetionString)

	Try

		connection.Open()

		Command = New SqlCommand(Sql, connection)

		adapter.SelectCommand = command

		adapter.Fill(ds)

	Catch ex As Exception

		MessageBox.Show("No es pot obrir!")

	End Try

	Dim oRpt As New ReportDocument()

	oRpt.Load("C:\Users\Josep\Desktop\report_nou.rpt")

	oRpt.SetDataSource(ds)

	CrystalReportViewer1.ReportSource = oRpt

End Sub