index administration status

Hello all,

I have problems with my index administration status. Sometimes the status is green and sometimes red. But I do always the same things. I select all my indizes and click "reindex". After this process I select all indzes and click "incremental update". So, after that I go to Monitoring -> KM -> TREX -> queue status change and I let all indizes work out (in German it means "Abarbeiten" - I don't know if "work out" is the correct translation). The index monitor is OK and there are no errors.

The application protocol in systemconfig -> KM -> index administration shows also no errors!

If I go over the status icon I can see an error (something like a data source could not been correct indexed).

Why have I such problems? What is my mistake?

Kind regards and thanks in advance

Susa