Drupal contributed modules problem

I extracted a contributed module into the sites/all/modules folder, but it is not yet appeari开发者_开发问答ng in my admin panel under Administer -> Site building -> Modules. What could be the problem?

I tried clearing the cache, it made no difference.

Did you extract the file structure correctly?

e.g.

sites/all/modules/[module name]/[files]

What about permissions? Have you set at least read permissions for the web server on these directories? Perhaps try

chmod -R 755 sites/all/modules

Also, ensure that you are using the correct version of the module, e.g. 6.x modules only work on Drupal 6.x installs