Teamviewer 6 has been decommissioned by Teamviewer.
Consequently all users need to install the Teamviewer 9 quicksupport module
1: Use this link
https://community.teamviewer.com/t5/Knowledge-Base/Download-TeamViewer-8-and-9/ta-p/78348
2: Download and run the 'Quick Support'
3: Let us know the user ID number and Password via email