diff --git a/webapp/models/DynData.php b/webapp/models/DynData.php
index 1aa4d4d5..82e1e9d2 100644
--- a/webapp/models/DynData.php
+++ b/webapp/models/DynData.php
@@ -159,7 +159,7 @@ class DynData extends BaseModel {
     private static function internalGetV($x, $y, $defVal = 0)
     {
         $key = self::calcKey($x, $y);
-        if (self::$dynData) {
+        if (!is_null(self::$dynData)) {
             if (isset(self::$dynData[$key])) {
                 return self::$dynData[$key];
             } else {
@@ -172,7 +172,7 @@ class DynData extends BaseModel {
             ++self::$hitCount;
             if (self::$hitCount > 5 && is_null(self::$dynData)) {
                 self::preload();
-                return self::getV($x, $y, $defVal);
+                return self::internalGetV($x, $y, $defVal);
             } else {
                 $row = SqlHelper::ormSelectOne(
                     myself()->_getSelfMysql(),