WINCC tag-value is "???"

[Greet]

In some screens, the tags are not 'updated'.
If then i look into the Tagmamangement: the values and quality codes are "???" (See picture in attachment)

If then I put a string in the comment (see red box): the values becomes good.

Any idea?

 

[Lare]

Is there hidden characters on end of tag name?
WinCC is polling tags only when necessary or if tag is logged.
It is possible that your screen has different tag than on tag editor so tags are never scanned.
When you make change to tag, it is maybe polled one time after saved.