diff --git a/src/main/java/org/gcube/accounting/analytics/persistence/couchbase/AccountingPersistenceQueryCouchBase.java b/src/main/java/org/gcube/accounting/analytics/persistence/couchbase/AccountingPersistenceQueryCouchBase.java
index a4023d1..871ce66 100644
--- a/src/main/java/org/gcube/accounting/analytics/persistence/couchbase/AccountingPersistenceQueryCouchBase.java
+++ b/src/main/java/org/gcube/accounting/analytics/persistence/couchbase/AccountingPersistenceQueryCouchBase.java
@@ -614,7 +614,9 @@ AccountingPersistenceBackendQuery {
 				as(orderingProperty));
 		
 		
-		selectExpressions.add(x(getSpecializedProperty(clz,key)).as(key));
+		//selectExpressions.add(x(getSpecializedProperty(clz,key)).as(key));
+		selectExpressions.add(x("(CASE WHEN " + getSpecializedProperty(clz,key) + 
+				" IS NOT NULL THEN "+getSpecializedProperty(clz,key)+" ELSE 'UNKONW' END )").as(key));
 
 		//add where expression
 		Expression whereExpression = 
diff --git a/src/test/java/org/gcube/accounting/analytics/persistence/couchbase/AccountingPersistenceQueryCouchBaseTest.java b/src/test/java/org/gcube/accounting/analytics/persistence/couchbase/AccountingPersistenceQueryCouchBaseTest.java
index ba5458e..2abe452 100644
--- a/src/test/java/org/gcube/accounting/analytics/persistence/couchbase/AccountingPersistenceQueryCouchBaseTest.java
+++ b/src/test/java/org/gcube/accounting/analytics/persistence/couchbase/AccountingPersistenceQueryCouchBaseTest.java
@@ -22,6 +22,7 @@ import org.gcube.accounting.analytics.persistence.AccountingPersistenceBackendQu
 import org.gcube.accounting.analytics.persistence.AccountingPersistenceQuery;
 import org.gcube.accounting.datamodel.aggregation.AggregatedJobUsageRecord;
 import org.gcube.accounting.datamodel.aggregation.AggregatedServiceUsageRecord;
+import org.gcube.accounting.datamodel.aggregation.AggregatedStorageUsageRecord;
 import org.gcube.accounting.datamodel.usagerecords.JobUsageRecord;
 import org.gcube.common.scope.api.ScopeProvider;
 import org.json.JSONException;
@@ -130,17 +131,25 @@ public class AccountingPersistenceQueryCouchBaseTest  {
 	
 	@Test 
 	public void getQuerableKey() throws Exception{
-		SortedSet<String> keys = AccountingPersistenceQuery.getQuerableKeys(AggregatedJobUsageRecord.class);
-		logger.debug("keys:"+keys);
+		SortedSet<String> keys;
+
+		keys = AccountingPersistenceQuery.getQuerableKeys(AggregatedJobUsageRecord.class);
+		for (String key : keys) {
+			if (key != null && !key.isEmpty()) {
+				logger.debug("key:" +key);
+			}
+		}
+		logger.debug("List FilterKeys:" + keys.toString());
+		
 		
 	}
 	
 	@Test
 	public void testTopService() throws Exception {
 		Calendar startTime = Calendar.getInstance();
-		startTime.set(2016, Calendar.AUGUST, 25);
+		startTime.set(2015, Calendar.AUGUST, 25);
 		Calendar endTime = Calendar.getInstance();
-		endTime.set(2016, Calendar.AUGUST, 28,23,59);
+		endTime.set(2016, Calendar.SEPTEMBER, 28,23,59);
 
 
 		List<Filter> filters = new ArrayList<Filter>();
@@ -155,7 +164,7 @@ public class AccountingPersistenceQueryCouchBaseTest  {
 		SortedMap<NumberedFilter, SortedMap<Calendar, Info>>  set = 
 				accountingPersistenceQueryCouchBase.getTopValues(
 						clz, temporalConstraint, filters, 
-						AggregatedServiceUsageRecord.HOST, null);
+						AggregatedServiceUsageRecord.CALLERQUALIFIER, null);
 
 		logger.debug("Result final{}", set);