One of those blacks should be brining power to the device, and one will be taking the power to whatever the switch will be controlling. The wire brining in power would go to one of the black screws. The wire brining power out would go to your brass screw. The white wires can go to the silver screw, and you would keep the brass tab intact.
From what you said it does, I think you got the two black wires mixed up. If you switch the two black wires around (so the one you originally connected to the common terminal is connected to A1 and vice versa), without making any other changes, the outlet should work whether the switch is on or off.