diff --git a/entity/Observation_entity/Observation_entity.aod b/entity/Observation_entity/Observation_entity.aod
index 42aa711708f462f3261b1c663e7a67a14545e0b2..94c246c8b0020bd5deeac8479ed5aad7fbef0453 100644
--- a/entity/Observation_entity/Observation_entity.aod
+++ b/entity/Observation_entity/Observation_entity.aod
@@ -60,7 +60,6 @@
       <stateProcess>%aditoprj%/entity/Observation_entity/entityfields/object_type/stateProcess.js</stateProcess>
       <valueProcess>%aditoprj%/entity/Observation_entity/entityfields/object_type/valueProcess.js</valueProcess>
       <displayValueProcess>%aditoprj%/entity/Observation_entity/entityfields/object_type/displayValueProcess.js</displayValueProcess>
-      <onValueChange>%aditoprj%/entity/Observation_entity/entityfields/object_type/onValueChange.js</onValueChange>
     </entityField>
     <entityField>
       <name>OBJECT_ID</name>
@@ -142,6 +141,7 @@
       <name>OBJECT_FIELD</name>
       <title>Fields</title>
       <contentType>TEXT</contentType>
+      <mandatory v="true" />
       <dropDownProcess>%aditoprj%/entity/Observation_entity/entityfields/object_field/dropDownProcess.js</dropDownProcess>
       <selectionMode>MULTI</selectionMode>
       <stateProcess>%aditoprj%/entity/Observation_entity/entityfields/object_field/stateProcess.js</stateProcess>
diff --git a/entity/Observation_entity/entityfields/object_type/onValueChange.js b/entity/Observation_entity/entityfields/object_type/onValueChange.js
deleted file mode 100644
index 9bcd9261bdd4b363f261de9b5e1edad733a7b9ea..0000000000000000000000000000000000000000
--- a/entity/Observation_entity/entityfields/object_type/onValueChange.js
+++ /dev/null
@@ -1,6 +0,0 @@
-import("system.neon");
-import("Observation_lib");
-import("system.vars");
-
-if (vars.get("$sys.operatingstate") == neon.OPERATINGSTATE_NEW)
-    vars.set("$field.OBJECT_FIELD",null);
\ No newline at end of file