Read a little further down.  It's all in the syntax, you have to specify a
property name and value.
From the org manual:

C-c a m
Match: BIB_AUTHOR="Walter Evensong"


On Fri, Oct 30, 2015 at 8:13 AM Georg Otto <g.otto@ucl.ac.uk> wrote:

> Dear all,
>
> I am trying to filter my entries in agenda view by properties
>
> According to the orgmode manual, this can be done with C-c a m
>
> However for me, C-c a m filters only on tags, not on properties. Also
> the commands C-c / m and C-c \ give me an error, saying they are
> undefined.
>
> Has anybody an idea what is going on? How can I filter properties in
> agenda view. and vice versa, how can I exclude a property from agenda
> view?
>
> I am running emacs 24.3.1 and orgmode 7.9.3f
>
> Cheers,
>
> Georg
>
>
>