Automatic discovery and polled virtual machines on esx device don't work

Hi.

The Observium version is 23.9 but not listed above.

The automatic discovery of VMs don't work. I can't enable virtual-machine module for the esx device. The GUI interface is refreshed but the option stay on disabled.

But when I launch discovery.php  manually with -m virtual-machines option, the VM Tab appears with the list of VMs. 

Thank you in advance for your help.