Figured by myself..
in the file core / templates / chapter_template.php is missing the feature..
add at the end of the file this:
$CHAPTER_TEMPLATE['grid']['listPages']['start'] = "<div class='row'>";
$CHAPTER_TEMPLATE['grid']['listPages']['item'] = "<div class='col-xs-12 col-md-4 text-center'>
{CPAGETITLE}
<h2><a href='{CPAGEURL}' >{CPAGEMENU}</a></h2><p>{CHAPTER_DESCRIPTION}</p></div>";
$CHAPTER_TEMPLATE['grid']['listPages']['end'] = "</div>";
and the trik is done.
love