Is it possible to install the Jtweet extension in the Inside Out template?

Because I cannot install it.

On uploading I have this message:

* It was not possible to copy the selected file.
* JInstaller::install: Failed to copy file: /var/www/vhosts/webtrial.nl/subdomains/web/httpdocs/tmp/install_4d3e80f6dbb55/mod_jTweet.php to /var/www/vhosts/webtrial.nl/subdomains/web/httpdocs/modules/mod_jTweet/mod_jTweet.php

All directories are open (777)

Can you install any other modules?

My guess is that it is a permissions issue, with the server blocking the attempt because file permissions are too lax. All directories should have 755 permissions.