invalid argument

[AN-net]

im getting invalid argument for some reason:
heres the error

Originally Posted by php

Warning: Invalid argument supplied for foreach() in /home/blah/blah/blah/quiz.php on line 140

PHP Code:

137:        $fquestions= $DB_site->query("SELECT quiz_questions.question,quiz_questions.question_id,quiz_answers.answer,quiz_answers.correct FROM ".TABLE_PREFIX."quiz_questions LEFT JOIN quiz_answers ON (quiz_questions.question_id=quiz_answers.question_id) WHERE quiz_questions.quiz_id='".$_REQUEST['q']."' AND quiz_questions.active='1' AND quiz_answers.active='1'");
138:        while($question= $DB_site->fetch_array($fquestions))
139:        {
140:            foreach($question['answer'] as $answer)
141:            {
142:                exec_switch_bg();
143:                eval('$ansbits .= "' . fetch_template('quiz_correctansbits') . '";');
144:            }