Cannot install any CU

Hi,

I'm using SharePoint 2013 Server. When I run (Get-Spfarm).Buildversion , it gives me 15.0.4701.1000

I tried to install (April 2015 CU) , (May 2015 CU), (November 2015 CU). It didn't work because it doesn't find the right version number. So I run the update with : PACKAGE.BYPASS.DETECTION.CHECK=1

The install run fine, then I ran the psconfig.exe . (by the way the databases shows as no upgrade is required). When it's finished, I run again the (get-spfarm).Buildversion and it gives me the same version as before: 15.0.4701.1000

Any idea what is wrong here? Any help is much appreciated.

Thank you.

-Mehdi