diff --git a/PaintingPC/FrmQuality.cs b/PaintingPC/FrmQuality.cs
index d957e2d..b27b865 100644
--- a/PaintingPC/FrmQuality.cs
+++ b/PaintingPC/FrmQuality.cs
@@ -48,7 +48,7 @@ namespace PaintingPC
             _stationType = ConfigurationManager.AppSettings["Position"].ToString();
             string disableButtons = ConfigurationManager.AppSettings["DisableButtons"].ToString();
             string single = ConfigurationManager.AppSettings["SingleStation"].ToString();
-            string _isTest = ConfigurationManager.AppSettings["测试"].ToString();
+            string _isTest = ConfigurationManager.AppSettings["测试"]?.ToString();
             if (single == "true")
             {
                 _isSingleStation = true;