diff --git a/src/main/java/org/gcube/portlets/user/td/expressionwidget/client/ReplaceArithmeticWidget.java b/src/main/java/org/gcube/portlets/user/td/expressionwidget/client/ReplaceArithmeticWidget.java
index 781484c..d97c03d 100644
--- a/src/main/java/org/gcube/portlets/user/td/expressionwidget/client/ReplaceArithmeticWidget.java
+++ b/src/main/java/org/gcube/portlets/user/td/expressionwidget/client/ReplaceArithmeticWidget.java
@@ -73,7 +73,7 @@ public class ReplaceArithmeticWidget extends SimpleContainer {
 	private VerticalLayoutContainer vert;
 
 	private String readableExpression;
-	private String itemIdComboArithmetic;
+	private String itemIdComboOperation;
 	private String itemIdComboLeaf;
 	private String itemIdComboColumns;
 	private String itemIdFirstArg;
@@ -213,7 +213,7 @@ public class ReplaceArithmeticWidget extends SimpleContainer {
 	}
 
 	protected void setup() {
-		itemIdComboArithmetic = "ComboArithmetic" + trId.getId();
+		itemIdComboOperation = "ComboOperation" + trId.getId();
 		itemIdComboLeaf = "ComboLeaf" + trId.getId();
 		itemIdComboColumns = "ComboColumns" + trId.getId();
 		itemIdFirstArg = "FirstArg" + trId.getId();
@@ -403,6 +403,7 @@ public class ReplaceArithmeticWidget extends SimpleContainer {
 								firstArg.setEmptyText("");
 								secondArg.setVisible(false);
 								secondArg.setEmptyText("");
+								removeOperator(source);
 								break;
 							case Addition:
 							case Subtraction:
@@ -480,7 +481,7 @@ public class ReplaceArithmeticWidget extends SimpleContainer {
 
 		comboReplaceArithmeticElementsOperators.setEmptyText("Select...");
 		comboReplaceArithmeticElementsOperators
-				.setItemId(itemIdComboArithmetic);
+				.setItemId(itemIdComboOperation);
 		comboReplaceArithmeticElementsOperators.setWidth(COMBO_WIDTH);
 		comboReplaceArithmeticElementsOperators.setEditable(false);
 		comboReplaceArithmeticElementsOperators
@@ -689,6 +690,7 @@ public class ReplaceArithmeticWidget extends SimpleContainer {
 								firstArg.setEmptyText("");
 								secondArg.setVisible(false);
 								secondArg.setEmptyText("");
+								removeOperator(source);
 								break;
 							case Addition:
 							case Subtraction:
@@ -766,7 +768,7 @@ public class ReplaceArithmeticWidget extends SimpleContainer {
 				});
 
 		comboReplaceArithmeticElementsOperator.setEmptyText("Select...");
-		comboReplaceArithmeticElementsOperator.setItemId(itemIdComboArithmetic);
+		comboReplaceArithmeticElementsOperator.setItemId(itemIdComboOperation);
 		comboReplaceArithmeticElementsOperator.setWidth(COMBO_WIDTH);
 		comboReplaceArithmeticElementsOperator.setEditable(false);
 		comboReplaceArithmeticElementsOperator
@@ -861,7 +863,7 @@ public class ReplaceArithmeticWidget extends SimpleContainer {
 		horiz = (HBoxLayoutContainer) vert.getWidget(index);
 		@SuppressWarnings("unchecked")
 		ComboBox<ReplaceArithmeticElement> comboOperator = (ComboBox<ReplaceArithmeticElement>) horiz
-				.getItemByItemId(itemIdComboArithmetic);
+				.getItemByItemId(itemIdComboOperation);
 		Log.debug("combo Operator: " + comboOperator.getCurrentValue());
 		@SuppressWarnings("unchecked")
 		ComboBox<ReplaceArithmeticElement> comboLeaf = (ComboBox<ReplaceArithmeticElement>) horiz
diff --git a/src/main/java/org/gcube/portlets/user/td/expressionwidget/client/ReplaceWidget.java b/src/main/java/org/gcube/portlets/user/td/expressionwidget/client/ReplaceWidget.java
index 51b1550..eedef1e 100644
--- a/src/main/java/org/gcube/portlets/user/td/expressionwidget/client/ReplaceWidget.java
+++ b/src/main/java/org/gcube/portlets/user/td/expressionwidget/client/ReplaceWidget.java
@@ -381,6 +381,7 @@ public class ReplaceWidget extends SimpleContainer {
 								firstArg.setEmptyText("");
 								secondArg.setVisible(false);
 								secondArg.setEmptyText("");
+								removeConcat(source);
 								break;
 							case Concat:
 								if (!existConcat(source)) {
@@ -642,6 +643,7 @@ public class ReplaceWidget extends SimpleContainer {
 								firstArg.setEmptyText("");
 								secondArg.setVisible(false);
 								secondArg.setEmptyText("");
+								removeConcat(source);
 								break;
 							case Concat:
 								if (!existConcat(source)) {
diff --git a/src/main/java/org/gcube/portlets/user/td/expressionwidget/shared/replace/ReplaceArithmeticType.java b/src/main/java/org/gcube/portlets/user/td/expressionwidget/shared/replace/ReplaceArithmeticType.java
index 32fe618..654ba54 100644
--- a/src/main/java/org/gcube/portlets/user/td/expressionwidget/shared/replace/ReplaceArithmeticType.java
+++ b/src/main/java/org/gcube/portlets/user/td/expressionwidget/shared/replace/ReplaceArithmeticType.java
@@ -14,10 +14,10 @@ public enum ReplaceArithmeticType {
 	SubstringByCharSeq("Substring by Char Seq."),
 	TextReplaceMatchingRegex("Replace Matching Regex"),
 	Addition("Addition"),
-	Subtraction("Substring by Index"),
-	Modulus("Substring by Char Seq."),
-	Multiplication("Replace Matching Regex"),
-	Division("Replace Matching Regex");
+	Subtraction("Subtraction"),
+	Modulus("Modulus"),
+	Multiplication("Multiplication"),
+	Division("Division");
 	
 	/**
 	 * @param text