ANS - Verification Hash not working?

[JustinMichael Torok]

My ANS system just stopped working out of the blue. When I checked my logs, the "VerifyKey" reads as: "VerifyKey= HTTP/1.1" 200 - "-" "-""  Isn't there supposed to be a 40-character hash code?  I did a bit of debugging, and my PHP script always fails at the verification hash step.  This is my verification code:

$myDDHash = $_SERVER['HTTP_X_ANS_VERIFY_HASH'];
$myCalcHash = sha1($_SERVER['QUERY_STRING'] . $Salt);
if ($myDDHash == $myCalcHash) {

}

I left out the code that operates after a successful verification.

Anyone know what's going on?