Insert a keyframe to fix the tween creating a looping

Insert a keyframe to fix the tween.
Creating a Looping Animation
Your flame should flicker back and forth continuously for as long as the logo is onscreen.
You can create a seamless loop by making the first and last keyframe identical, and by putting
the animation inside a movie clip symbol. A movie clip timeline loops continuously,
independently of the main Timeline.
Duplicating keyframes
Make the first keyframe identical to the last keyframe by duplicating its contents.
1. Right-click the first keyframe on the flame layer and select Copy Frames. Or choose
Edit > Timeline > Copy Frames.

The contents of the first keyframe are placed on your clipboard.
2. Right-click the last keyframe on the flame layer and select Paste Frames. Or choose
Edit > Timeline > Paste Frames.
The first and last keyframes now contain identical flame shapes.
Tip
You can quickly duplicate keyframes by first selecting a keyframe and then
Alt/Option-dragging the keyframe to a new position.
Previewing the loop
Use the Loop button at the bottom of the Timeline to preview your animation.
1. Click the Loop button at the bottom of the Timeline, or choose Control > Loop
Playback (Alt+Shift+L/Option+Shift+L) to enable continuous playback when you play
the movie.
Markers appear on the Timeline header indicating the range of frames that loop during
playback. Next, adjust the markers to extend the loop to include the entire movie.
Note
The Loop Playback option loops only in the Animate CC authoring environment,
and not when it is published. To create a loop, put your animation in a movie clip
symbol, or use a this.gotoAndPlay() command for ActionScript 3.0
documents or for an HTML5 Canvas document, as described in the later lessons
on interactivity.

2. Extend the markers to include all the frames on your Timeline (frames 1 through 40),
or click the Modify Markers button and choose Marker Range All.
3. Press Enter/Return to test the animation.
The flame animation plays and loops continuously. Click the Pause button or press
Enter/Return again to stop the animation.
Inserting the animation into a movie clip
When your animation plays in a movie clip symbol, the animation loops automatically.
1. Select all the frames on the flame layer, and right-click and choose Cut Frames. Or,
choose Edit > Timeline > Cut Frames.
The keyframes and shape tweens are removed from the Timeline and placed on the
clipboard.
2. Choose Insert > New Symbol (Ctrl+F8/Command+F8).
The Create New Symbol dialog box appears.
3. Enter flame as the name of the symbol, and choose Movie Clip as the Type. Click OK.

A new movie clip symbol is created and opens in symbol-editing mode.
4. Right-click the first frame on your movie clip timeline and select Paste Frames. Or,
choose Edit > Timeline > Paste Frames.
The flame animation from the main Timeline is pasted into your movie clip symbol’s
timeline.