diff --git a/ErgometerApplication/ErgometerApplication/MainClient.cs b/ErgometerApplication/ErgometerApplication/MainClient.cs
index a286051..87e659c 100644
--- a/ErgometerApplication/ErgometerApplication/MainClient.cs
+++ b/ErgometerApplication/ErgometerApplication/MainClient.cs
@@ -166,7 +166,7 @@ namespace ErgometerApplication
             
 
             Metingen.Add(m);
-            if (Doctor.Connected)
+            if (Doctor != null && Doctor.Connected)
             {
                 NetHelper.SendNetCommand(Doctor, new NetCommand(m, Session));
             }