Ocdata owncloud

I’ve installed yunohost on raspeberry wihtout problems.
I’ve also installed owncloud and its running with datas on “local”

I’ve try to change the directory on external hard drive as explained on the page

But I have the following message when I try to connect to owncloud :
The directory (/media/Medias/owncloud/data) is not valid
Check the file “.ocdata” on the roots.

The directory and the file .ocdata exists, the permissions are corrects.

I’ve try everything since two days without success…