Can't register screen with server

Hey there,
I believe i’m seeing the same issue (but do correct me if not). I just upgraded from 7.1 to 7.4 and i seem to be unable to register new clients. The CMS runs on a Windows server and the client also is a windows (8.1) client running the correct (1.7.4) client.

When i click “Save” on the client, i get “Display is awaiting licensing approval from an Administrator”. However, the machine entry does not appear in the “Displays” list in the CMS. The Log shows:

788827 15-09-17 09:28:09 CMS Data Class: Error Number [25004] Error Message [Cannot find display record]

I generated a “troubleshoot.txt” file and the only thing odd that i can see are a few erroneous entries for non-existant and un-named displays. These don’t appear in my list in the CMS and i wonder if this is my problem?

DisplayID: 15
Display:
Default Layout:
Logged In: 0
Last Accessed: 1442403025
Interleave: 0
Licensed: 0

DisplayID: 16
Display:
Default Layout:
Logged In: 0
Last Accessed: 1442476854
Interleave: 0
Licensed: 0

DisplayID: 17
Display:
Default Layout:
Logged In: 1
Last Accessed: 1442478234
Interleave: 0
Licensed: 0

I did used to distribute a pre-built config file with the client installer which omitted the hardware key and the station name, which Xibo replaced dynamically during registration. Although this worked in 7.1, i wonder if the 7.4 client no longer replaces a blank name with the computername… As it stands now, i can add new clients even with no distributed xml file.

Thanks in advance