diff --git a/src/main/java/org/gcube/portlets/user/td/gwtservice/server/opexecution/OpExecution4DataMinerOperation.java b/src/main/java/org/gcube/portlets/user/td/gwtservice/server/opexecution/OpExecution4DataMinerOperation.java
index d2e82cb..09271b0 100644
--- a/src/main/java/org/gcube/portlets/user/td/gwtservice/server/opexecution/OpExecution4DataMinerOperation.java
+++ b/src/main/java/org/gcube/portlets/user/td/gwtservice/server/opexecution/OpExecution4DataMinerOperation.java
@@ -1,5 +1,6 @@
 package org.gcube.portlets.user.td.gwtservice.server.opexecution;
 
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -16,7 +17,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- * Operation DataMiner 
+ * Operation DataMiner
  * 
  * @author "Giancarlo Panichi" email: <a
  *         href="mailto:g.panichi@isti.cnr.it">g.panichi@isti.cnr.it</a>
@@ -27,15 +28,14 @@ public class OpExecution4DataMinerOperation extends OpExecutionBuilder {
 			.getLogger(OpExecution4DataMinerOperation.class);
 
 	private TabularDataService service;
-	//private ServiceCredentials serviceCredentials;
+	// private ServiceCredentials serviceCredentials;
 	private DataMinerOperationSession dataMinerOperationSession;
 
-
-	public OpExecution4DataMinerOperation(
-			TabularDataService service,ServiceCredentials serviceCredentials,
+	public OpExecution4DataMinerOperation(TabularDataService service,
+			ServiceCredentials serviceCredentials,
 			DataMinerOperationSession dataMinerOperationSession) {
 		this.service = service;
-		//this.serviceCredentials = serviceCredentials;
+		// this.serviceCredentials = serviceCredentials;
 		this.dataMinerOperationSession = dataMinerOperationSession;
 	}
 
@@ -49,14 +49,16 @@ public class OpExecution4DataMinerOperation extends OpExecutionBuilder {
 
 		operationDefinition = OperationDefinitionMap.map(
 				OperationsId.StatisticalOperation.toString(), service);
-		
-		//map.put(Constants.PARAMETER_DATAMINER_GCUBETOKEN, serviceCredentials.getToken());
-		map.put(Constants.PARAMETER_DATAMINER_OPERATOR, dataMinerOperationSession.getOperator());		
-		
+
+		// map.put(Constants.PARAMETER_DATAMINER_GCUBETOKEN,
+		// serviceCredentials.getToken());
+		map.put(Constants.PARAMETER_DATAMINER_OPERATOR, Collections
+				.singletonMap(Constants.PARAMETER_DATAMINER_OPERATOR,
+						dataMinerOperationSession.getOperator()));
+
 		invocation = new OperationExecution(
 				operationDefinition.getOperationId(), map);
 
-		
 		operationExecutionSpec.setOp(invocation);
 
 	}