yii2 checkbox is not showing but label is visible

     <?= $form->field($model, 'term_condition')->checkbox(); ?>

It is not showing the checkbox but it shows the label.

and I looked into the generated html and that is also fine.here is the generated html.

<div class="form-group field-dynamicmodel-term_condition">
<input type="hidden" name="DynamicModel[term_condition]" value="0"><label> . 
    <input type="checkbox" id="dynamicmodel-term_condition" 
     name="DynamicModel[term_condition]" value="1"> Term Condition</label>
<div class="help-block"></div>