Previous Fan Failure Message!/ Dimension 4300

I have been getting a "Previous Fan Failure! Press F1 to Continue or F2 to go to the setup menu" message, and so I figured I needed a new fan. I bought one (one made for Dell, same specs and everything), and then installed it. After installing it I turned on my computer and still got the same message...someone help me please? I'm growing tired of seeing that message every time I turn my computer on.