Can't install

Do you have safe_mode on?
Can you install other components?

No, safe_mode is off. I'm able to install other components.

Then it's pretty strange. Have you tried installing it from directory?

I have, but I must be doing something wrong. Here's what I tried:

--ftped the unzipped folder to the components folder
--renamed it com_sefadvanced
--replaced the .htaccess file
--changed the permissions of install.sef.php to 666 (then 777)
--pointed the browser to:

myjoomladirectory/components/com_sefadvanced/install.sef.php

All I got was a blank screen. And nothing shows in administrator

Where did I go wrong?

That would not work.
Do this instead:

- Upload unzipped files to ./media/sef_advance/
- Go to Joomla components installer, Install from directory, and point it to:
/path/media/sef_advance/
- Click on "Install"

Well, some progress. But problems persist.

After changing the permission on the installer.class.php file, I got it installed. However, although I uninstalled OpenSEF, cleaned the cache and reinstalled SEF Advance several times, my website is not functional and the browser displays this message:

We are really sorry, but our sef_ext.php file is provided only for the OpenSEF component. You can install the OpenSEF component, remove the sef_ext.php file or write the sef_ext.php for the SEF component which do You use

When I checked this file in the SEF Advance folder, it is the one for SEF Advance. Nothing to do with OpenSEF. And I can't find any other such file.