Tomtom Mount Tomtom Dashdoard Mount?

Tomtom dashdoard mount? - tomtom mount

I have a TomTom. He came with a mounting kit (suction cup). I would like on the scoreboard (received no windshield) on. So I bought a bag made of plastic which sticks to the dashboard. The problem is when I connect using the suction cup to the platform, it will remain for some time, but then go!
How can I secure it on the dashboard?