diff --git a/ykval-verify.php b/ykval-verify.php
index cfacbe6..55ce004 100644
--- a/ykval-verify.php
+++ b/ykval-verify.php
@@ -150,6 +150,11 @@ if (!isset($sl) || $sl == '')
 {
 	$sl = $baseParams['__YKVAL_SYNC_DEFAULT_LEVEL__'];
 }
+if ($sl && (preg_match("/^[0-9]+$/", $sl)==0 || ($sl<0 || $sl>100)))
+{
+	$myLog->log(LOG_NOTICE, 'SL is provided but not correct');
+	sendResp(S_MISSING_PARAMETER, $myLog);
+}
 
 if (!isset($timeout) || $timeout == '')
 {
@@ -200,12 +205,6 @@ if (isset($nonce) && (strlen($nonce) < 16 || strlen($nonce) > 40))
 	sendResp(S_MISSING_PARAMETER, $myLog);
 }
 
-if ($sl && (preg_match("/^[0-9]+$/", $sl)==0 || ($sl<0 || $sl>100)))
-{
-	$myLog->log(LOG_NOTICE, 'SL is provided but not correct');
-	sendResp(S_MISSING_PARAMETER, $myLog);
-}
-
 /**
  * Timestamp parameter is not checked since current protocol
  *	says that 1 means request timestamp and anything else is discarded.