diff --git a/MainWindow.xaml.cs b/MainWindow.xaml.cs
index 2384ed9..a6a84cf 100644
--- a/MainWindow.xaml.cs
+++ b/MainWindow.xaml.cs
@@ -4,6 +4,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Text.RegularExpressions;
+using System.Threading;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Data;
@@ -105,24 +106,22 @@ namespace SUNLIGHT_CDKEY
 
         private void Button_Click(object sender, RoutedEventArgs e)
         {
-
             string a;
             string b, my, mm, md;
 
-            if (sn_id.Text == "") return;
+            if (sn_id.Text.Length <6)
+            {
+                sn_id.BorderBrush = new SolidColorBrush(System.Windows.Media.Color.FromArgb(255, 255,0, 0));
+                return;
+            }else sn_id.BorderBrush = new SolidColorBrush(System.Windows.Media.Color.FromArgb(255, 255, 255, 255));
 
-            a= sn_id.Text.Substring(0, 6);
+            a = sn_id.Text.Substring(0, 6);
        
             my = Convert.ToString(Convert.ToInt32(2255 - y), 16).ToUpper();
             mm = Convert.ToString(Convert.ToInt32(255 - m), 16).ToUpper();
             md = Convert.ToString(Convert.ToInt32(255-d), 16).ToUpper();
             b=my+mm+md;
 
-
-            a= sn_id.Text.Substring(0, 6);
-            b=(2255-y).ToString()+(255-m).ToString()+(255-d).ToString();
-
-
             cdk.Text = a + b + CRCcheck16.ToCRC16(CRCcheck16.StringToHexByte(b), true);
         }