How to take a value from span tag to scriplet tag

I am trying this id="captcha" to read in scriplet tag in jsp...ANY help will be appreciated thankyou Below code follow from span tag...this span tag give the random generated value but when taken to sciplet tag it give null. Please help

<span id="captcha">captext</span><img src="images/refreshimg.jpg" class="imgrefresh"  onClick="window.location.reload();"/>

<%     
    String idone=request.getParameter("captext");
    out.println(idone); //WHY NULL IS COMING
   %>