OS X Server - Update server

Hello

On my OS X Server, when a software update is available on the appstore I can upload it without any issue

But I do not know why, my OS X computers which are connected on the OS X server for the update management, did not see the software update when available on the server.

Example : I do not have on my computer the update available for itunes and OS X, when already downloaded on my server since few days or weeks