error after install MySQL Fulltext Search v0.4 in 1.3 beta2

From http://fluxbb.org/trac/browser/extensio … k/fulltext

when i'm trying to search

Fatal error: Call to undefined function utf8_strlen() in C:\AppServ\www\flux\include\search_functions.php(37) : eval()'d code on line 14

<? if ( preg_match('/^.{1}$/u',"ñ",$UTF8_ar) != 1 )
    exit('Bad');
else
    exit('OK'); ?>

i got ok

and when i'am trying to uninstall this extension

Fatal error: Call to undefined method DBLayer::drop_index() in C:\AppServ\www\flux\admin\extensions.php(347) : eval()'d code on line 8

~.~ how to fix it for 1.3beta2

Thank you.