Variables from flash to php.

I want to send variables out of a flash file and use them in a php page.

The actionscript currently stands as.....

varsToSend = new LoadVars();
      varsToSend.table_name = "tblPilot";
      varsToSend.Response="it_" + item + ":res_" + resp + ":rt_" + rt + ":sq_" + seq;
      varsToSend.confirmation_page = "http://test-extranet.edfac.unimelb.edu.au/arc_test_dev/Problem%20Solving%20Items/index.php";
      varsToSend.send("ItemProc.php","_self","POST");



and the PHP is

echo $_POST['Item_0026_Response'];


it does not print the variable as expected. Can anyone tell me why?