Anybody help with this form?

[timmah1]

I have a form, I'm only going to show a little part

 

I'm just starting to learn AJAX, and I'm getting stuck

<select name="plumbing" id="plumbing" onClick="plumbingUser(this.value)">
            <option></option>


    <option value="<?php echo $row['name']; ?>"><?php echo $row['name']; ?></option><br />

</select>
</td>
        </tr>
      </table></td>
  </tr>
  <tr>
    <td>HVAC Contractor</td>
    <td><table width="600" cellpadding="5" cellspacing="0">
        <tr>
          <td width="200">
            <div id="hvacHint"><b><?php echo $row9['hvac_contractor']; ?></b></div></td>

          <td width="200">
          <select name="hvac" id="hvac" onClick="hvacUser(this.value)">
          <option>--</option>
          <option value="an">Add New</option>
          <option>--</option>
    <option value="<?php echo $row['id']; ?>"><?php echo $row['name']; ?></option><br />

</select>

 

Here is the part that is suppose to bring out the values

var xmlHttp

function hvacUser(str)
{ 
xmlHttp=GetXmlHttpObject()
if (xmlHttp==null)
{
alert ("Browser does not support HTTP Request")
return
}
var url="getuser.php"
url=url+"?q="+str
url=url+"&sid="+Math.random()
xmlHttp.onreadystatechange=stateChanged 
xmlHttp.open("GET",url,true)
xmlHttp.send(null)
}

function stateChanged() 
{ 
if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
{ 
document.getElementById("hvacHint").innerHTML=xmlHttp.responseText 
} 
}

function plumbingUser(str)
{ 
xmlHttp=GetXmlHttpObject()
if (xmlHttp==null)
{
alert ("Browser does not support HTTP Request")
return
}
var url="getplumbing.php"
url=url+"?p="+str
url=url+"&sid="+Math.random()
xmlHttp.onreadystatechange=stateChanged 
xmlHttp.open("GET",url,true)
xmlHttp.send(null)
}

function stateChanged() 
{ 
if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
{ 
document.getElementById("plumbingHint").innerHTML=xmlHttp.responseText 
} 
}

 

The problem is, I think 'plumbingHint' is overriding the 'hvacHint' because where the hvac is suppose to show, nothing shows, but the hvac shows where plumbing is suppose to go, and nothing happens when I click on anything where the plumbing is.

 

Can anybody shed some light on what I'm doing wrong?

 

Thanks in advance