Issue with OCS Inventory (no machines in DB)

Hello all,

I installed OCS today in CentOS 7 and a client in a Windows 8.1 computer.

If I go in the server (http://ocs001/ocsreports)>All computers I can see this computer.

But (that's the issue) if I go to the main page, I see the following:

Machines in DB                                           0
Machines Inventoried                                    0
Machines contacted today                            0
Machines Inventoried today                           0
Machines not seen in more than 30 day(s)     0
Number of SNMP devices                             0

What can it happen?

Many thanks!