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In the past week or so I tried pinging other members, but the system doesn't seem to work for me.
Here for example I am writing @Jochen I am trying to ping a member with the handle Jochen, and it doesn't seem to work, here my comment that doesn't seem to present the pinged username of Jochen. A claim in Krengel's book on Ergodic Theorems.
How to fix this?