Not reading Instances in the homepage

Change-Id: Id23da7018f89d306424d22897d3436063bf4133a
diff --git a/src/app/datasources/stores/model.store.ts b/src/app/datasources/stores/model.store.ts
index 7da92f6..e3deda3 100644
--- a/src/app/datasources/stores/model.store.ts
+++ b/src/app/datasources/stores/model.store.ts
@@ -148,7 +148,7 @@
     subject.next(subject.value);
   }
 
-  private loadInitialData(model: string, apiUrl?: string) {
+  private loadInitialData(model: string, apiUrl: string) {
     // TODO provide always the apiUrl together with the query() params
     if (!angular.isDefined(apiUrl)) {
       apiUrl = this.XosModeldefsCache.getApiUrlFromModel(this.XosModeldefsCache.get(model));