mm_forum

While performing a search, class tx_mmforum_pi1 is not found:

Fatal error: Class 'tx_mmforum_pi1' not found in typo3conf/ext/mm_forum/pi4/class.tx_mmforum_pi4.php on line 441
Call Stack
#    Time    Memory    Function    Location
1    0,0002    68888    {main}( )    ../index.php:0
2    0,0010    211672    require( '/typo3/sysext/cms/tslib/index_ts.php' )    ../index.php:80
3    0,2290    18749252    tslib_fe->INTincScript( )    ../index_ts.php:448
4    0,2336    19565456    tslib_fe->INTincScript_process( )    ../class.tslib_fe.php:3175
5    0,2338    19609428    tslib_cObj->USER( )    ../class.tslib_fe.php:3236
6    0,2339    19611448    tslib_cObj->callUserFunction( )    ../class.tslib_content.php:789
7    0,2340    19616012    call_user_func_array ( )    ../class.tslib_content.php:6626
8    0,2340    19616012    tx_mmforum_pi4->main( )    ../class.tslib_content.php:0
9    0,2410    20092804    tx_mmforum_pi4->searchfind( )    ../class.tx_mmforum_pi4.php:108

require_once(t3lib_extMgm::extPath('mm_forum') . 'pi1/class.tx_mmforum_pi1.php');

Better: Use autoloader from 4.3!