How to open page inside the div and make the inputs of this internal page work?

I made a page index that calls another page within div . But I came across a simple problem: the page appears inside div of page index , where I have a search field, except that clicking the button or a enter in the field does not loads the function. I ran a test with this page that calls within%% of% separated and div loads, but calling it within%% of index page does not load function.

My code is below:

//esse javascript é o que chama a pagina dentro da <div>
<script>
function display_c(){
    setInterval('getInfo()',30000);
}
function getInfo(){
    var xmlhttp;
    if (window.XMLHttpRequest)
    {// code for IE7+, Firefox, Chrome, Opera, Safari
        xmlhttp = new XMLHttpRequest();
    }
    else
    {// code for IE6, IE5
        xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    xmlhttp.onreadystatechange = function() {
        if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
            document.getElementById("conteudo").innerHTML = xmlhttp.responseText;
        }
    };
    xmlhttp.open("GET", "MRB_Dados.php?op=<?php echo $op;?>", true);
    xmlhttp.send();
}

$.post('MRB.php',function(html){
    $('#coteudo').html(html);
});
</script>

//aqui é a <div> que vai receber a pagina.

<div id="conteudo"></div>

//e esse é os inputs que eu chamo da outra pagina que vai aparecer dentro da <div>.

<section>
   <table border="0" align="center">
       <tr>
        <td width="300">
          <input type="search" placeholder="" id="bs-prod"/>
            <input type="hidden" name="str" id="str" value="aqm"/>
              <input type="hidden" name="str" id="str" value="aqm"/></td>
         <td>
         &nbsp;<input class="btn btn-danger" type="submit" value=" Pesquisar ">
                <input type="hidden" name="pesquisar" value="sim">
       </td>
     </tr>
   </table>
 </section>