[R] problem with "code/documentation mismatch"

[Joerg van den Hoff]

I have a package with a division method for special objects of class 
"RoidataList", i.e. the function is named `/.RoidataList'.
documentation for this is in the file "Divide.RoidataList".


R CMD CHECK complains with:

=================cut======================
* checking for code/documentation mismatches ... WARNING
Functions/methods with usage in documentation object 
'Divide.RoidataList' but not in code:
   /

* checking Rd \usage sections ... WARNING
Objects in \usage without \alias in documentation object 
'Divide.RoidataList':
   /
=================cut======================

the `usage' section in the Rd file reads

=================cut======================
\usage{
    x/y
}
=================cut======================

which, of course is the desired way to use the function.
what am I doing wrong, i.e. how should I modify the Rd file?
maybe obvious, but not to me.

joerg van den hoff