Simple question about $.post and a PHP sum

Question

I have a jQuery $.post function sending data to a PHP file which updates a DB field, grabs 1 of the values being sent to the file, adds '1' and returns the new value.

My PHP file looks as follows:

$varID = $_GET['varID'];
$varKey = $_GET['varKey'];
$varCurrentValue = ($_GET['varCurrentValue'] + 1);

update_comment_meta($varID, $varKey, $varCurrentValue);

echo $varCurrentValue;

My firebug response, if I'm understanding it correctly, confirms that the value's are being sent correctly to the PHP file: http://cl.ly/2P1Y0E3710442V3I143K [img]

However the only response that I'm getting is the "1" that I'm adding in the 3rd line of code, not the value of the sum that I should be getting.

I'm sure it's something really simple, but I'm just not seeing it...

Thanks for your help!