jQuery serialize with Ajax does not work in IE9

function myTimestamp(){  
    tstmp = new Date();      
    return tstmp.getTime(); 
}   
function showValues() {  
    var str = ($("#this").serialize());  
    $("#results").text(str);  
}  
$(":checkbox, :radio").click(showValues);  
$("select").change(showValues);  
showValues();  
function sendValues() {  
    var str = $("#this").serialize();  
    var response = $('input[name=product[]]:checked').val();  
    $.ajax({  
        url: "/post.php?avoidcache=' + myTimestamp();",  
        data: {str}  
        cache: false  
    });  
}

This script works wonderful in Google Chrome; however when using in IE it only will execute one of the selected elements: the rest of开发者_开发百科 the selected elements get cut off. Any suggestions?

<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7" />