reCaptcha回调：未启用删除禁用属性的功能

Question

伙计们，我正在尝试通过recaptcha回调从按钮中删除disable属性，但该属性通过脚本为true时却不起作用。有人可以帮忙吗？代码如下。

function recaptchaCallback(){
	$('#btnSubmit').removeAttr('disabled');
}

<form>    
<fieldset>
        <!-- reCaptcha -->
 
      
    <div class="form-group text-center">
    <label class="col-md-4 control-label"></label>
    	<div class="g-recaptcha col-md-4"   data-sitekey="6Lf3JDAUAAAAAJ3Y4oPhVeuAx0K98sCCYju7HcT1" ></div    <input type="hidden" class="form-control" data-recaptcha="true" required>
        <div class="help-block with-errors"></div>
    </div>
  

    <!-- Button -->
     <div class="form-group text-center">
      <label class="col-md-4 control-label"></label>
      <div class="col-md-4"><br>
        <button id="btnSubmit" name="btnSubmit" type="submit"  value="Submit" class="btn btn-success" data-callback="recaptchaCallback" disabled>SUBMIT <span class="glyphicon glyphicon-send"></span></button>
      </div>
    </div>
    

    
    </fieldset>
    </form>