Problem with postback inside the onchange event of dropdown

Problem with postback inside the onchange event of dropdown

Hi,

I'm using version jquery.mobile-1.2.0.
I have a dropdown in my form and when I select an item I want to fire a postback.
The code is below:

<script type="text/javascript">

        function cmbSiteChange() {
            __doPostBack('', 'CmbSiteChg');
        }
</script>
.....
.....
<div data-role="page" id="page1">
      <div data-role="content">
            <select data-native-menu="false" name="" data-mini="true" id="cmbSite" runat="server"
               onchange="cmbSiteChange();">
            </select>
......
......

Everything goes fine in IE, I select an item and the onchange event is fired and it executes the postback.
But if I try to do the same thing in firefox or chrome I can't do the postback. I mean, the onchange event is fired, but the postback is not.

If I change the property data-native-menu to true, it works fine in all browsers: IE, Firefox, Chrome...

I'd like to have this property set to false. 
And I'd like to use any type of browser: IE, Safari, Chrome, Firefox, Opera...
What can I do, so I can fire a postback in the onchange event with this property set to false?

Thank you