Ms project ressource leveling automatic split

Hello, 

I am trying to use the feature of Ms project that automatically split remaining work to do with a resource.

Here is a very basic example not leveled yet: 

• start date of test 1 is 14/12/23
• start date of test 2 is 07/12/23
• priority of test 1 (900) is higher than test 2 (800)

I would like test2 to start before and then split the remaining work when we need to start test 1

I did the following things: 

• Check box in leveling options  "leveling can create splits in remaining work" is checked 
• Column "Leveling can split" ies set to Yes

However when I do leveling it does not split any task to optimize the duration of the project.

here is the output when I press Level All

Could you help me ?