diff --git a/src/main/java/org/gcube/informationsystem/model/knowledge/ModelKnowledge.java b/src/main/java/org/gcube/informationsystem/model/knowledge/ModelKnowledge.java
index f42c5ee..7c1c1e9 100644
--- a/src/main/java/org/gcube/informationsystem/model/knowledge/ModelKnowledge.java
+++ b/src/main/java/org/gcube/informationsystem/model/knowledge/ModelKnowledge.java
@@ -57,6 +57,7 @@ public class ModelKnowledge<T, TI extends TypeInformation<T>> {
 		
 		this.trees = new HashMap<>();
 		this.erTypesUsage = new HashMap<>();
+		this.locate = new HashMap<>();
 		
 		AccessType[] modelTypes = AccessType.getModelTypes();
 		for(AccessType accessType : modelTypes) {
@@ -169,8 +170,6 @@ public class ModelKnowledge<T, TI extends TypeInformation<T>> {
 		Tree<T> tree = trees.get(accessType);
 		tree.addNode(t);
 		
-		
-		
 		UsageKnowledge<LinkedEntity> resourceUsage = erTypesUsage.get(AccessType.RESOURCE);
 		UsageKnowledge<LinkedEntity> facetUsage = erTypesUsage.get(AccessType.FACET);
 		UsageKnowledge<LinkedEntity> isRelatedToUsage = erTypesUsage.get(AccessType.IS_RELATED_TO);