diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/ws/orders/impl/OrderElementConverter.java b/navalplanner-webapp/src/main/java/org/navalplanner/ws/orders/impl/OrderElementConverter.java
index 87aaacca0..402f08e5e 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/ws/orders/impl/OrderElementConverter.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/ws/orders/impl/OrderElementConverter.java
@@ -426,6 +426,11 @@ public final class OrderElementConverter {
                     .getMaterialCategory();
             material.setCategory(defaultMaterialCategory);
 
+            /*
+             * "validate" method avoids that "material" goes to the Hibernate's
+             * session if "material" is not valid.
+             */
+            material.validate();
             Registry.getMaterialDAO().save(material);
         }
 
@@ -447,6 +452,11 @@ public final class OrderElementConverter {
             throw new RuntimeException(e);
         } catch (InstanceNotFoundException e) {
             labelType = LabelType.create(labelDTO.type);
+            /*
+             * "validate" method avoids that "labelType" goes to the Hibernate's
+             * session if "labelType" is not valid.
+             */
+            labelType.validate();
             Registry.getLabelTypeDAO().save(labelType);
         }
 
diff --git a/navalplanner-webapp/src/test/java/org/navalplanner/web/test/ws/orders/OrderElementServiceTest.java b/navalplanner-webapp/src/test/java/org/navalplanner/web/test/ws/orders/OrderElementServiceTest.java
index a5cfe7237..540aaecc4 100644
--- a/navalplanner-webapp/src/test/java/org/navalplanner/web/test/ws/orders/OrderElementServiceTest.java
+++ b/navalplanner-webapp/src/test/java/org/navalplanner/web/test/ws/orders/OrderElementServiceTest.java
@@ -48,7 +48,6 @@ import org.hamcrest.Description;
 import org.hamcrest.Matcher;
 import org.joda.time.LocalDate;
 import org.junit.Before;
-import org.junit.Ignore;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.navalplanner.business.IDataBootstrap;
@@ -425,7 +424,6 @@ public class OrderElementServiceTest {
                 equalTo(previous + 1));
     }
 
-    @Ignore
     @Test
     public void orderWithInvalidMaterialAssignment() {
         int previous = orderDAO.getOrders().size();
@@ -444,8 +442,9 @@ public class OrderElementServiceTest {
 
         List<ConstraintViolationDTO> constraintViolations = instanceConstraintViolationsList
                 .get(0).constraintViolations;
-        // Mandatory fields: material, units, unitPrice
-        assertThat(constraintViolations.size(), equalTo(3));
+        // Mandatory fields: material code
+        assertThat(constraintViolations.size(), equalTo(1));
+        assertThat(constraintViolations.get(0).fieldName, mustEnd("code"));
 
         assertThat(orderDAO.getOrders().size(), equalTo(previous));
     }