Arrange checkbox field in active form [solved]

Hi, i have checkbox field (transfer field) in active form, but the position is ugly. see attachment.
how to arrange so it is same line with its beside 2 fields?

Thanks before.

<?php $form = ActiveForm::begin(); ?>
    <div class="row">
        <div class="col-xs-4">
            <?= $form->field($model, 'contract_no')->textInput(['maxlength' => true]) ?>
        <div class="col-xs-6">
            <?= $form->field($model, 'realisasi_date')->widget(kartik\widgets\DatePicker::className(),
                    'type' => kartik\widgets\DatePicker::TYPE_COMPONENT_APPEND,
                    'pluginOptions' => [
                        'autoclose' => true,
                        'format' => 'yyyy-mm-dd'
                ]) ?>
        <div class="col-xs-2">
            <?= $form->field($model, 'transfer')->checkbox() ?>

I have solved it by doing this.

<div class="col-xs-4">
            <label class="control-label" for="realisasiproduksi-transfer">&nbsp;</label>
            <?= $form->field($model, 'transfer')->checkbox() ?>
            <div class="help-block"></div>