When you say light is on when car is off do you mean the parking light? Check the pins where the wires go into the bulb socket, perhaps one isnt making a good connection. Or hook up a test light to the brake bulb socket and see if it illuminates.

If I remember, the wiring goes from d/side and then loops over to the passenger side so looks like a test light "chase" is in order, check all rear lights, lic plate etc. Not to sound insulting but check the simple stuff again...correct bulbs., did you seat them properly into the socket?

Wish I could help more

Pooly