That's it! Try adjusting the gain and base speed of your line follower to see how fast you can get your robot to follow the line without falling off. If your robot is doing the exact opposite of what it is supposed to (i.e. constantly turning away from the line), you have a sign error somewhere in your program. You can fix this by switching you "Add" and "Subtract" functions, throwing a negative in front of your gain, or simply moving to the other side of the line.