After effects loop part of movie clip I have one movie clip and it has few events which I want to repeat for few times. I used this and similar other tutorial to achieve this. Ideally I tried following,


Select Clip and Pre-compose it (so that I can use that repeating
part independently. I have tried without pre-compose also and got
same result) 
Right click > time > enable time-remapping
Goto the expression panel (alt click clock symbol)
Put expression as loopOut() and click outside
Create keyframe between between start and end of my desired clip part


However, this doesn't work. Can anyone tell me what I am doing wrong?

To better explain the my desired output, lets assume I have 5 min video clip (===) and I want part from 3 to 4 min (+++) to repeat 2 times. 


  0 ====3+++4====5


So now my video should become 6 min with clip from 3 to 4 min repeated twice.


  0 ====3+++4+++5====6


I am using Adobe After Effects CC 2019.
LoopOut() loops after the last keyframe, and by default it loops all the keyframes. Unless you have a specific need to use expressions, this would be easier to achieve by just setting keyframes. 


Once you have time remapping enabled, go to the 3 minute mark and add a keyframe. 
Then go to the frame one frame before 4 minute mark and add another. 
Select the last three keyframes (3 minutes, 4 minutes and 5 minutes in your example). 
Copy them ctrlc. 
Delete the last keyframe
Park the playhead one frame after the 4 minute keyframe and paste ctrlv. The 3 minute keyframe should be at the exact 4 minute mark. Since the timing of the subsequent keyframes is undisturbed, the video will run at the right speed.


Your keyframes should look like this:

0=====3+++④3+++④=====5 ←keyframes 
0.....3....4....5....6 ←time


(the ④ indicates the frame one frame before the four minute mark)


for extra credit change the first 4 minute keyframe (the one that has the 3 minute keyframe right after it) to a hold keyframe (Right-click and Toggle Hold Keyframe). This is because if you have motion blur or frame blending on it can cause strangeness as the layer is "rewound" between the two keyframes.