[Orgmode] sparse-tree in indirect buffer

[Stuart McLean]

Hi,

First some background, I am using
GNU Emacs 22.1.1 (x86_64-pc-linux-gnu, GTK+ Version 2.10.13) of 2007-08-21 on 
excelsior, modified by Debian
and org-mode version 5.13a

I have headings like (for example)
* September
** similar stuff to October
* October
** Oct 1
*** Work
    :PROPERTIES:
    :CATEGORY: work
    :END:
**** work info
** Oct 2
    :PROPERTIES:
    :CATEGORY: work
    :END:
**** work info
** Oct 3
    :PROPERTIES:
    :CATEGORY: work
    :END:
**** work info
** Oct 4
    :PROPERTIES:
    :CATEGORY: work
    :END:

and so on.

I want to display the subtree in an indirect buffer, so I type `C-c C-x b'

Now, _from the indirect buffer_ I want a sparse tree as follows `C-c
/' (org-sparse-tree) and at the prompt I type `p', enter the property
name "CATEGORY" with the value "work"

The message in the echo area is Wrong type argument: stringp, nil

and in the *Messages* buffer:

abbreviate-file-name: Wrong type argument: stringp, nil

I would like to be able to get a sparse tree from an indirect buffer, is this 
possible? And if it is not, should the message be more informative e.g. "Please 
call sparse tree from blah blah"?

Sorry if this is noise,

org-mode is fantastic btw :-)

Stuart