You're the one who needs clearing out Clavat
To expand what Cannis said, the full name of the rules file you are editing should be "rulesmd.ini". The "md" part means "mission disk" - i.e. this is a Yuri's Revenge file (as opposed to non-Yuri's Revenge) and will only be used for the YR expansion. The ".ini" part is not part of the actual name - it's the file extension (or file format to use another word for it). Going into the realm of uber-n00bness now... a file has a name and extension... the extension is always ".ext" where "ext" tells the computer what kind of file it is - e.g. "txt" means it's a text file that can be read in notepad, "jpg" is a... jpeg file, "exe" is a program that the computer can run (such as RA2) and the rules file needs to have the extension ".ini" for RA2/YR to read it. Make sure you do not hide file extensions (as Cannis said), otherwise when you rename a file it will simply change the NAME part of the complete filename, not the EXTENSION part of the filename.
So.... yeah. This is really basic stuff. I hope you already know it
