input 창 length가 0이 돼면 체크박스를 해제하고 싶습니다.

      <?php if ($is_email) { ?>
      <span class="emailArea">
      <div class="subject">이메일</div>
      <label for="wr_email" class="sound_only">이메일</label>
      <input onKeyPress="emailAni()" tabindex="4" style="width:132px;" tabindex="4" type="text" name="wr_email" value="<?php echo $email ?>" id="wr_email" class="allInput half_input email" placeholder="이메일" alt="이메일" title="이메일">
      </span>
      <?php } ?>

         if($('input:text[name="wr_email"]').length == 0){
             $('input:checkbox[name="mail"]').prop('checked',false);
         }

뭐가 틀린거죠?