When I try to install I have that error message:

DateTime::__construct() [datetime.--construct]: Failed to parse time string (jerror) at position 0 (j): The timezone could not be found in the database

Please install Admin Tools from www.akeebabackup.com/ in order to fix your permissions as they should be and then reinstall the extension.

Right permissions on all joomla sites:
755 for folders
644 for files

The permissions are 755 for folders and 644 for files. The PHP version is 5.3.25. The message is 0 DateTime::__construct() [datetime.--construct]: Failed to parse time string (jerror) at position 0 (j): The timezone could not be found in the database

Fixed! I turned off the open_basedir tweak on my site. The discussion  is here: www.joomlashine.com/forum/showthread.php?39145-DateTime-Error-when-installing

But can't install after that. I got Warnings and Error when tryed to install:


Warning

Warning: Failed to move file!

JFolder: :files: Path is not a folder. Path: /home/mysitelogin/public_html/tmp/install_51a2d5125b0be

JFolder: :folder: Path is not a folder. Path: /home/mysitelogin/public_html/tmp/install_51a2d5125b0be

JFolder: :files: Path is not a folder. Path: /home/mysitelogin
JInstaller: :Install: Cannot find Joomla XML setup file

Error

Archive does not exist

And I can't find a XML file in the olugin.

Admin Tools can fix any read/write "file" permissions on your site, to what they should be. But, if your server's "owner" permissions for files are not properly setup, in other words, if Joomla cannot perform read/write operations via PHP, then it will not work properly. Either enable the Joomla! FTP layer or better still, contact your hosting company and ask them to fix any "owner" related permission issues.