My Privateers are not firing?

Hi everyone. I feel that this is somehow a stupid question, but I am a total noob with Civ 5. Anyway, I'm attacking Bucharest and I have 4 Privateers jammed right up on their coast, but when I give them the attack command they do absolutely nothing. I thought I read in my research that they were made to attack coastal cities. I'm doing something wrong, that's for sure, I just don't know what.

Any ideas why I can't attack? Thank you so much for your time.

The actual city must be on the coast, the privateer must be in contact with the city, not just the borders.

Thank you, that explains a lot. I wonder if you might suggest a city as an example, that is directly on the coast - no borders?

At least one of the 6 tiles immediately adjacent to the city center must be a coastal tile.

Thank you Browd. That info will also be quite useful.

Also, unlike Frigates, Privateers are not ranged units and must melee attack.