Ok i undertand.
I will modifying my workflow.
I used before sample chains with one shot but never try sample chains with loops.
It can be really nice if I map the « slice number » to my Midi controller that I already use for volume tracks and FX2 send.
Now I need to create sample chains with my many many loops all with the same length?
Thx for your help guys 
CC#017
Not necessarily required if you are using Slices [ Setup Param B = SLIC ] as then the start points can be variable and controlled with Slice Number [ Param B] . As opposed to not, where the Start Parameter [ Param B] will be Start.
Yes advantage with sample chains : you don’t have silent gaps. But I’m surprised the Fn+Arrow thing works for me. My good old OT must be very fast. 
Same length if you want to create sample chains for Start mode : advantage : 128 loops max, vs 64 for Slice mode. You need 128 loops, not less.
With Slice mode you can have less loops. If you have less than 64 slices and set Slice number above, the slice with the highest number is played.
You can do your sample chains with softwares like @Rusty’s OctaEdit, or @Abhoth’s Octachainer.
Just to say THANKS all who helped me on my issues. 
So i followed your advices and I decided to use this technique instead:
It works, it’s stable, no more fucking « file not found », more reliable, practical and faster.
It’s a bite long and like @sezare56 said in the French forum it’s gave an headache to make the entire process from A to Z (i use ableton and Octachainer) BUT when your megabreak of doom works it’s just awesome 
Thanks again all for your time and your help 
“Error : Megabreak not found” 
Hahahaha 
I will map the « slice number » parameter to my midi controller an old UC33 (love it since many years).
@sezare56 can you remember me the CC# please. 
Oops you have mentioned it sry 
For the Megabreak, depending on slices number, you may have to use the crossfader’s CC48. If you always use 64 slices, CC17 will suffice.
I had the UC33 too, efficient and cheap standalone controller. 
Where’s that?
Audiofanzine Octatrack Forum.
Na, - you, my good old friend, are simply too slow 
I’m very fast. We can go up to 600 bpm with my OT. 
Heart attacks? Sometimes…