FORM : Auto submit VS click to submit

FORM : Auto submit VS click to submit

Can anybody tell me Why I click on button to submit form -> it works, but
when I use javascript to auto submit -> it failed ?
I have this form on aaa.com, it submit to bbb.com/result.jsp (another domain)
<form id="myForm" name="myForm " method="post"
action="www.bbb..com/result.jsp">
<input name="var01" value="var01 ">
<input name="var02" value="var02 ">
<input type="submit" name="searchButton" value="Search">
</form>
Manually click on Search button, result.jsp works fine.
When I added following script, result.jsp page doesn't work
<script>
document.getElementById("myform").submit();
</script>