Excusez-moi, monsieur?

I don't know what we're doing wrong.

Sometimes, Michael and I go out for dinner. That, I believe, is not unusual.
We arrive. We are shown to a table and are given menus to peruse. Usually, then someone comes to ask us if we're ready, to which the answer is usually 'Can we please have a few more minutes?'. We subsequently order and receive appropriate courses in a timely fashion.
Then... and here's where the problem arises... nothing happens. We have clearly finished. Empty dessert dishes and coffee cups are cleared. And then the 'how do we get the bill' dance begins. There follows several minutes of trying to catch the eye of a waiter, putting a wallet/purse on the table, etc... and still no bill. Other tables receive their bills, pay and are off into the night. Not us. Eventually we end up practically grabbing the sleeve of a passing waiter to request the bill, at which point they seem totally surprised to see us still there and go to get it. It seems that eating a nice meal renders the pair of us utterly invisible.

I don't know what we're doing wrong. Any ideas?