diff --git a/Symcon_Publish_to_Shelly_MQTT/form.json b/Symcon_Publish_to_Shelly_MQTT/form.json
index 6fc805e..5cef90b 100644
--- a/Symcon_Publish_to_Shelly_MQTT/form.json
+++ b/Symcon_Publish_to_Shelly_MQTT/form.json
@@ -43,7 +43,8 @@
     {
       "type": "SelectVariable",
       "name": "switch_bool",
-      "caption": "Variable mit dem zu regelnden Shelly Kontakt"
+      "caption": "Variable mit dem zu regelnden Shelly Kontakt",
+      "validVariableTypes": [0]
     }
     
   ]
diff --git a/Symcon_Publish_to_Shelly_MQTT/module.php b/Symcon_Publish_to_Shelly_MQTT/module.php
index 96d6960..ff3bc27 100644
--- a/Symcon_Publish_to_Shelly_MQTT/module.php
+++ b/Symcon_Publish_to_Shelly_MQTT/module.php
@@ -17,7 +17,7 @@ class Symcon_Publish_to_Shelly_MQTT extends IPSModule
         $this->RegisterPropertyInteger("msg_id", 1);
         $this->RegisterPropertyString("src", "user1");
         $this->RegisterPropertyString("method", "Switch.Set");
-        $this->RegisterPropertyBoolean("switch_bool", false);
+        $this->RegisterPropertyInteger("switch_bool", 0);
 
 
     }
@@ -50,7 +50,7 @@ class Symcon_Publish_to_Shelly_MQTT extends IPSModule
         $msg_id = GetValue($this->ReadPropertyInteger("msg_id"));
         $src = GetValue($this->ReadPropertyString("src"));
         $method = GetValue($this->ReadPropertyString("method"));
-        $switch_bool = GetValue($this->ReadPropertyBoolean("switch_bool"));
+        $switch_bool = GetValueBoolean($this->ReadPropertyInteger("switch_bool"));
         // JSON-Payload erstellen
         $payload = [
             "id" => 0,