the captcha validation is using the wrong session for comparison, it is using the session name "captcha_Security_Code" it should be using the session named "captcha_Security_Code_1". change line 21:
$WAFV_Errors .= WAValidateLE((strtolower(isset($_POST["Security_Code"])?$_POST["Security_Code"]:"")) . "",((isset($_SESSION["captcha_Security_Code"]))?strtolower($_SESSION["captcha_Security_Code"]):"") . "",true,10);
to:
$WAFV_Errors .= WAValidateLE((strtolower(isset($_POST["Security_Code"])?$_POST["Security_Code"]:"")) . "",((isset($_SESSION["captcha_Security_Code_1"]))?strtolower($_SESSION["captcha_Security_Code_1"]):"") . "",true,10);