Question on notifications

Hi,

From the documentation I was able to build a trigger firing upon deletion of a record a function that delivers tablename_operation as a notification one needs to subscribe to. So in terminal I can say LISTEN persons_delete and instantly will receive

Asynchronous notification "persons_delete" received from server process with PID 54790.

if there was a delete. But what I don't fully understand is how to do this with PQnotifies. Following the docu I get no notifications even though I subscribe to them after successfully connecting to the server the same way I do using terminal.

Googling didn't give me examples I was able to use. Please, can someone help?

Thanks
Alex