[BioC] where is the "getHomolog" function in biomaRt?

[zrl]

Dear list,

After asking how to do cross specices annotation. I tried BiomaRt, and
find there is direct function "getHomolog" described in its manual to
do this.

But when I try to use it, it gave me the error:

"Error: could not find function "getHomolog"

Could anyone explain this to me? where should I found a version with
this fucntion? Thanks.


-Roger