Topic on Extension talk:InviteSignup

I work with:

MediaWiki	1.22.4
PHP	5.3.28-pl3-gentoo (uwsgi)
MySQL	5.1.70

and I use last version of InviteSignup, fetched with git. I get this error:

[539c326f] /index.php/Special:InviteSignup Exception from line 376 of /var/www/wiki/htdocs/includes/SpecialPage.php: Call to undefined method SpecialInviteSignup::getPageTitle
Backtrace:
#0 /var/www/wiki/htdocs/extensions/InviteSignup/SpecialInviteSignup.php(136): SpecialPage->__call(string, array)
#1 /var/www/wiki/htdocs/extensions/InviteSignup/SpecialInviteSignup.php(136): SpecialInviteSignup->getPageTitle()
#2 /var/www/wiki/htdocs/extensions/InviteSignup/SpecialInviteSignup.php(82): SpecialInviteSignup->getAddRow()
#3 /var/www/wiki/htdocs/includes/SpecialPage.php(631): SpecialInviteSignup->execute(NULL)
#4 /var/www/wiki/htdocs/includes/SpecialPageFactory.php(488): SpecialPage->run(NULL)
#5 /var/www/wiki/htdocs/includes/Wiki.php(298): SpecialPageFactory::executePath(Title, RequestContext)
#6 /var/www/wiki/htdocs/includes/Wiki.php(602): MediaWiki->performRequest()
#7 /var/www/wiki/htdocs/includes/Wiki.php(467): MediaWiki->main()
#8 /var/www/wiki/htdocs/index.php(49): MediaWiki->run()
#9 {main}

What you can advise me?

Please update to the latest version where I have restored compatibility with MediaWiki 1.22

Thanks.