Key Mode lets you jump directly between keyframes in your animation. By default, Key Mode uses the keys visible in the track bar below the time slider. Other options are available on the Time Configuration dialog in the Key Steps group.
When the Auto Key button on and you change an object’s creation parameters or performed a transform, or change a material or modifier applied to that object, 3ds Max automatically creates a keyframe.
Key Mode can respect all keyframes, or you can restrict it to move only to transform keys via the Key Steps options on the
Time Configuration dialog. When Key Steps 
Use TrackBar is on, Key Mode jumps to keyframes of any type. When Use TrackBar is off, Key Mode respects only transform keys.
(Key Mode).
(Previous Key) and 
(Next Key) to move from one keyframe to the next.
If the current frame does not jump to the keys, make sure 
the animated object is selected in the viewport.
If it still doesn’t seem to be working, configure Key Mode to Use TrackBar, as described in the following procedure.
(Time Configuration), or right-click any animation-control button, including (Key Mode).
If you turn on Use TrackBar and turn Key Mode on, then clicking Next Key advances to the next key for the selected object. This will respect every type of key that appears in the track bar. If you turn Use TrackBar off, only transform keys are used by key mode.
