diff --git a/Symcon_Publish_to_Shelly_MQTT/module.php b/Symcon_Publish_to_Shelly_MQTT/module.php
index 1bba5e3..6b74647 100644
--- a/Symcon_Publish_to_Shelly_MQTT/module.php
+++ b/Symcon_Publish_to_Shelly_MQTT/module.php
@@ -13,7 +13,7 @@ class Symcon_Publish_to_Shelly_MQTT extends IPSModule
         $this->RegisterPropertyString("password", "");
         $this->RegisterPropertyString("Topic", "");
         $this->RegisterPropertyString("client_id", ""); 
-        $this->RegisterPropertyString("mqtt_instance_id", ""); 
+        $this->RegisterPropertyInteger("mqtt_instance_id", ""); 
         // Nachricht-Payload-Parameter als Properties
         $this->RegisterPropertyInteger("msg_id", 100);
         $this->RegisterPropertyString("src", "user1");