[Submit A Form With Select Menu Dropbox Without Submit Button]

I am working on a website with my project mates, in which I need to add a filter dropdown box. When I select one of the option in it, the table being displayed in that webpage will display a different set of data based on the type of data I selected to filter. Also this webpage can only be seen by logging in as a valid user.

 

I am very new to javascript and php programming and after going through several forums, I added the following code as a start to do the filtering, by which the webpage will be able to get the dropdown box option that was selected and display it:

 

 

<script>
function formSubmit()
{
document.getElementById("report_filter").submit();
}
</script>

<form method="POST" id="report_filter" action="" >
<select name="try" onchange="formSubmit();">
<option value="all">All</option>
<option value="Windows">Windows</option>
<option value="Win 2008">Win 2008</option>
<option value="Win 7">Win 7</option>
<option value="Win Vista">Win Vista</option>
<option value ="Linux">Linux</option>
<option value = "Win 7/Linux">Win 7/Linux</option>
</select>
</form>

<?php

if(!(isset($_POST["try"])))
{
  echo "none";
}
else
echo $_POST["try"];

?>

The code above works ok when i run that individually in a separate php page, i.e., it ehoes the option that i select in the drop down box. But not so when I add it to the webpage that I am working on, cause when I select an option in the dropdown box the page goes blank and nothing else happens.