[TYPO3] Installing a sysext

[Xavier Perseguers]

Hi,

Dmitry released an openid extension 
(http://bugs.typo3.org/view.php?id=9474) as t3x file but I cannot get it 
installed. I choose to install it as sysext.

I made sure sysext directory is writable (as well as ext/ - global), I 
activated it in localconf.php (otherwise I would not be able to choose 
this type of installation) but I keep getting an error message when 
uploading the file:

Error: The extension can only be installed in the path (lockType=system)

What do I miss?

-- 
Xavier Perseguers
http://xavier.perseguers.ch/en/tutorials/typo3.html