File System Error: Unable to create directory . (New Blog Templates - While copying files)

I get this error while creating a new site:

File System Error: Unable to create directory /home/obscured.nl/domains/obscured.nl/public_html/wp-content/blogs.dir/15/files. (New Blog Templates - While copying files)

The folder is owned by the linux user who own the hosting package.

I suspect that the software runs under apache but i cant confirm that as im a noob

I think that because auto upgrade of WP also did not work untill i filled the ftp details in wp-config