please, i buy the module, when i put in instal modules appears this message


Warning: JInstaller::require_once(/home/laguiamu/public_html/principal/libraries/joomla/installer/adapters/sef_ext.php) [jinstaller.require-once]: failed to open stream: No such file or directory in /home/laguiamu/public_html/principal/libraries/joomla/installer/installer.php on line 216

Fatal error: JInstaller::require_once() [function.require]: Failed opening required '/home/laguiamu/public_html/principal/libraries/joomla/installer/adapters/sef_ext.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/laguiamu/public_html/principal/libraries/joomla/installer/installer.php on line 216