diff --git a/src/main/java/org/gcube/portlets/user/td/gwtservice/server/opexecution/OpExecution4ChangeColumnsPosition.java b/src/main/java/org/gcube/portlets/user/td/gwtservice/server/opexecution/OpExecution4ChangeColumnsPosition.java
index 153d984..ab82b78 100644
--- a/src/main/java/org/gcube/portlets/user/td/gwtservice/server/opexecution/OpExecution4ChangeColumnsPosition.java
+++ b/src/main/java/org/gcube/portlets/user/td/gwtservice/server/opexecution/OpExecution4ChangeColumnsPosition.java
@@ -69,7 +69,13 @@ public class OpExecution4ChangeColumnsPosition extends OpExecutionBuilder {
 			logger.error("Error in change position: no column set");
 			throw new TDGWTServiceException("No column set");
 		}
+		
+		if (changeColumnsPositionSession.getColumns().size() <=1) {
+			logger.error("Error in change position: Columns <= 1");
+			throw new TDGWTServiceException("There are not enough columns");
+		}
 
+		
 		ArrayList<ColumnReference> columns = new ArrayList<ColumnReference>();
 		for (ColumnData col : changeColumnsPositionSession.getColumns()) {
 			ColumnLocalId columnId = new ColumnLocalId(col.getColumnId());