Why isn't my LSE activated?

[HMsDobby2]

Hello,

 

I'm using the nucleo-h743zi2 board.

I cannot select LSE in my clock configuration.

 

My board is currently in the state described in the following guide.

 

Does anyone know the reason?

 

Thank you in advance for any advice you can provide.

[HMsDobby2]

I found out the reason.
It was not set in RCC. Thank you.