When adjusting the Bezier handles on a keyframe, it is possible that you can "break" your handles. If you want them to join again, try the following:
Go to your interpolation dialog box. Context click on the keyframe for the floating menu, and change your Bezier Keyframe to a Continuous Bezier Keyframe.
Option Double Click on the Keyframe for the Keyframe Velocity Box and check the Continuous Bezier Box.
Bezier Keyframes have different incoming and outgoing velocities (broken handles) while Continuous Bezier Keyframes have the same incoming and outgoing velocities (joined handles).