diff --git a/screening/source/java/ch/systemsx/cisd/openbis/dss/screening/server/DssServiceRpcScreening.java b/screening/source/java/ch/systemsx/cisd/openbis/dss/screening/server/DssServiceRpcScreening.java
index dba71bab6dca4e627168f09fd147ce8886d93c00..db67b2573b149333196d2a79c88dbc8ada92cad2 100644
--- a/screening/source/java/ch/systemsx/cisd/openbis/dss/screening/server/DssServiceRpcScreening.java
+++ b/screening/source/java/ch/systemsx/cisd/openbis/dss/screening/server/DssServiceRpcScreening.java
@@ -24,6 +24,7 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -647,7 +648,7 @@ public class DssServiceRpcScreening extends AbstractDssServiceRpc<IDssServiceRpc
     public void checkDatasetsAuthorizationForIDatasetIdentifier(String sessionToken,
             List<? extends IDatasetIdentifier> identifiers)
     {
-        Set<String> dataSetCodes = new HashSet<String>();
+        Set<String> dataSetCodes = new LinkedHashSet<String>();
         for (IDatasetIdentifier identifier : identifiers)
         {
             dataSetCodes.add(identifier.getDatasetCode());
diff --git a/screening/sourceTest/java/ch/systemsx/cisd/openbis/dss/screening/server/DssServiceRpcScreeningTest.java b/screening/sourceTest/java/ch/systemsx/cisd/openbis/dss/screening/server/DssServiceRpcScreeningTest.java
index ced31af0b879117ff5591de427279d1c04598b50..f6891d279b8a1cfe11b7f4e8f0f1a6a4ab9cc277 100644
--- a/screening/sourceTest/java/ch/systemsx/cisd/openbis/dss/screening/server/DssServiceRpcScreeningTest.java
+++ b/screening/sourceTest/java/ch/systemsx/cisd/openbis/dss/screening/server/DssServiceRpcScreeningTest.java
@@ -369,6 +369,8 @@ public class DssServiceRpcScreeningTest extends AssertJUnit
         context.checking(new Expectations()
             {
                 {
+                    one(service).checkInstanceAdminAuthorization(SESSION_TOKEN);
+                    
                     one(transformerDAO).saveTransformerFactoryForChannel(EXPERIMENT_PERM_ID,
                             channel, transformerFactory);
                     one(transformerDAO).commit();
@@ -390,6 +392,8 @@ public class DssServiceRpcScreeningTest extends AssertJUnit
         context.checking(new Expectations()
             {
                 {
+                    one(service).checkInstanceAdminAuthorization(SESSION_TOKEN);
+                    
                     one(transformerDAO).saveTransformerFactoryForExperiment(EXPERIMENT_PERM_ID,
                             transformerFactory);
                     one(transformerDAO).commit();