textconv not used for diff

Hello,

After trying for a couple hours to get textconv to work according to
<https://git.wiki.kernel.org/index.php/Textconv> and other pages, I've
given up. I've tried changing .odt, .ott and .ods files, but git-diff
never outputs the text diff:

$ git --version
git version 1.7.0.4
$ cat ~/.gitattributes
*.odp diff=odf
*.ods diff=odf
*.odt diff=odf
*.ott diff=odf
$ cat ~/.gitconfig
...
[diff "odf"]
	textconv = odt2txt
$ odt2txt budget.ods
[produces useful output]
$ git diff

diff --git a/budget.ods b/budget.ods
index 64374b9..c4a1949 100644
Binary files a/budget.ods and b/budget.ods differ

$ git diff --textconv

diff --git a/budget.ods b/budget.ods
index 64374b9..e680dee 100644
Binary files a/budget.ods and b/budget.ods differ

Any ideas?

-- 
Victor Engmark