Connection to xxxxx denied, because remote TeamViewer is not visible

[ChrisR]

My father's computer appears in my online list, but when I try to establish remote control:
1. TeamViewer Authentication dialog box does not open.
2. the authentication status light turns from green to yellow to red (Authentication  rejected)
3. in the log "Connection to xxxx denied, because remote TeamViewer is not visible"

Unfortunately my father is nearly blind so he cannot provide any info on what is going on at his end (he can restart, and I assume TeamViewer continues to be a start up item).

It is strange that my TeamViewer "sees" my father's computer as online, but then it is "not visible" when I try to establish remote control

[Admin]

How long has this been happening. Sometimes there is a glitch in the server(teamviewers) and i run into this situation, it resolves itself after a day or so.
It may also be an issue of outdated teamviewer software, is there anyone on the remote side that can help you update the software?