when i made my self admin, the admin.dat stayed blank
Well, it is really simple:
Either you want to have different admin levels, in which case you have to read and follow the document behind the link. Or you don't want it, in which case you leave it blank. The answer was given to you either way.
I am not quite sure if the rcon admin is written to the admin.dat
If it is, there might be a second admin.dat in a different path. Try to search for "admin.dat" and see if you get more than one hit.