First, be sure you did what it's indicated on the Cloud9 support page, under the "IMPORTANT" heading:
http://www.fsdreamteam.com/products_cloud9.htmlIMPORTANT
If the Cloud9 product you purchased doesn't have an FSDT updated installer yet, you have to install the Cloud9 product first, then update the Stand-alone Addon Manager
Since the F104 doesn't have an FSDT installer, you must do the above, to get the latest version of the gauge files.
If you did that, so you are sure you are running the most current version of the files, then it's possible there are issues in Windows 8.1, which was never a supported OS for any of the FS9 product (we stopped supporting FS9 in 2011, a year before Windows 8 was released) so, while it's possible that something might still work, we cannot test it or guarantee it will.