Private UpdateThread As Thread
 
Private Sub FillCalendar()
        ...
        UpdateThread = New Thread(AddressOf ReadJobs)
        UpdateThread.Start()
        ...
End Sub

Private Sub ReadJobs()
        ReadingFinished = False
        Try
            objDataSet.Tables("Access").Clear()
        Catch ex As Exception
        End Try
        connAccess.Open()
        Try
                daAccess = New OleDbDataAdapter("SELECT * FROM Termine " & _
                "WHERE Datum = #" & Mid(dtpDatum.Value.ToString, 4, 2) & "-" & _
                Mid(dtpDatum.Value.ToString, 1, 2) & "-" & _
                Mid(dtpDatum.Value.ToString, 9, 2) & "#", connAccess)
                daAccess.Fill(objDataSet, "Access") '***
            Catch ex As Exception
                    MessageBox.Show(ex.ToString)
             End Try
             Call CloseAccess()
End Sub