Chown PRoblem..HELP PLEASE

[Ruel Luchavez]

Hi ALL,

i make a new directory in my server using "mkdir [name of folder], then when
i wan to view the folder i use "ll" and this is the view:

drwxrwxrwx 2 root wheel 512 Apr 11 11:05 [name of folder]

when i want to change the owner[root] into a certain name (ex.ruel) using
the command:

chown -R ruel:wheel ...path/[name folder]

I allways got and error:

chown:ruel: Invalid argument

what went wrong here guys? what could be my error? can you HELP me on this?
PLEASE...

your HELP is highly appreciated