diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/NoneFunction.java b/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/NoneFunction.java
new file mode 100644
index 000000000..2d16b9cf6
--- /dev/null
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/NoneFunction.java
@@ -0,0 +1,67 @@
+/*
+ * This file is part of NavalPlan
+ *
+ * Copyright (C) 2009-2010 Fundación para o Fomento da Calidade Industrial e
+ *                         Desenvolvemento Tecnolóxico de Galicia
+ * Copyright (C) 2010-2011 Igalia, S.L.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.navalplanner.business.planner.entities;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.navalplanner.business.planner.entities.allocationalgorithms.ResourcesPerDayModification;
+
+/**
+ *
+ * @author Diego Pino García <dpino@igalia.com>
+ *
+ *         Calculate hours per day for resource based on total amount of hours to
+ *         be done and number of resources per day
+ *
+ */
+public class NoneFunction extends AssignmentFunction {
+
+    public static NoneFunction create() {
+        return create(new NoneFunction());
+    }
+
+    protected NoneFunction() {
+
+    }
+
+    public String getName() {
+        return ASSIGNMENT_FUNCTION_NAME.NONE.toString();
+    }
+
+
+    public void applyTo(ResourceAllocation<?> resourceAllocation) {
+        apply(resourceAllocation);
+    }
+
+    private void apply(ResourceAllocation<?> resourceAllocation) {
+        int hours = resourceAllocation.getAssignedHours();
+
+        List<ResourcesPerDayModification> resourcesPerDayModification = Arrays.asList(resourceAllocation
+                    .asResourcesPerDayModification());
+
+        ResourceAllocation
+            .allocating(resourcesPerDayModification)
+            .untilAllocating(hours);
+    }
+
+}
\ No newline at end of file
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/ResourceAllocation.java b/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/ResourceAllocation.java
index 68e5b357a..e31a589a8 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/ResourceAllocation.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/ResourceAllocation.java
@@ -82,6 +82,8 @@ public abstract class ResourceAllocation<T extends DayAssignment> extends
 
     private static final Log LOG = LogFactory.getLog(ResourceAllocation.class);
 
+    private static final NoneFunction NONE_FUNCTION = NoneFunction.create();
+
     public static <T extends ResourceAllocation<?>> List<T> getSatisfied(
             Collection<T> resourceAllocations) {
         Validate.notNull(resourceAllocations);
@@ -1243,10 +1245,14 @@ public abstract class ResourceAllocation<T extends DayAssignment> extends
     }
 
     public void setAssignmentFunction(AssignmentFunction assignmentFunction) {
-        this.assignmentFunction = assignmentFunction;
-        if (this.assignmentFunction != null) {
-            this.assignmentFunction.applyTo(this);
+        // If the assignment function is empty, avoid creating an association
+        // between the resource allocation and the assignment function
+        if (assignmentFunction == null) {
+            NONE_FUNCTION.applyTo(this);
+            return;
         }
+        this.assignmentFunction = assignmentFunction;
+        this.assignmentFunction.applyTo(this);
     }
 
     private void setWithoutApply(AssignmentFunction assignmentFunction) {
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/allocation/AdvancedAllocationController.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/allocation/AdvancedAllocationController.java
index 0c1809b1a..6ba6ec961 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/allocation/AdvancedAllocationController.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/allocation/AdvancedAllocationController.java
@@ -48,6 +48,7 @@ import org.navalplanner.business.planner.entities.AssignmentFunction;
 import org.navalplanner.business.planner.entities.AssignmentFunction.ASSIGNMENT_FUNCTION_NAME;
 import org.navalplanner.business.planner.entities.CalculatedValue;
 import org.navalplanner.business.planner.entities.GenericResourceAllocation;
+import org.navalplanner.business.planner.entities.NoneFunction;
 import org.navalplanner.business.planner.entities.ResourceAllocation;
 import org.navalplanner.business.planner.entities.SigmoidFunction;
 import org.navalplanner.business.planner.entities.SpecificResourceAllocation;
@@ -1308,7 +1309,15 @@ class Row {
         public void applyDefaultFunction(
                 ResourceAllocation<?> resourceAllocation) {
             resourceAllocation.setAssignmentFunction(null);
+            reloadHours();
         }
+
+        private void reloadHours() {
+            reloadHoursSameRowForDetailItems();
+            reloadAllHours();
+            fireCellChanged();
+        }
+
     };
 
     private abstract class CommonStrechesConfiguration extends