尝试从另一个模型获取值，但它显示错误，表示未定义“Property”FeeRemissionGroup.class_english_name“。”

I try to get the value from ClassM model but it displays an error:

Property "FeeRemissionGroup.class_english_name" is not defined.

FeeRemissionGroup works, but can't get it from ClassM.

echo $form ->dropDownListRow($model, 'fee_remission_group_code', FeeRemissionGroup::model()->getFeeRemissionGroup(), array('class'=>'span3'));     
echo $form ->dropDownListRow($model, 'class_english_name', ClassM::model()->listClass(), array('class'=>'span5'));

Any solution to solve this problem?