Why isn't AdWords showing my ad?

Question

contextual advertising

I set up advertising, made an announcement, passed moderation. Google automatically bids. However, the ad is not showing, it says
Your keyword isn't triggering ads to appear on Google right now due to a low Ad Rank. Ads are ranked based on your bid and Quality Score.
My bid is automatic, see QS:
Quality score 6/10
Expected clickthrough rate: Average
Ad relevance: Average
Landing page experience: Average
This is a passing score, isn't it? What can be wrong?