diff --git a/AttributesAPI/src/org/gephi/data/attributes/type/IntervalTree.java b/AttributesAPI/src/org/gephi/data/attributes/type/IntervalTree.java
index 44dde3979..65e06e0af 100644
--- a/AttributesAPI/src/org/gephi/data/attributes/type/IntervalTree.java
+++ b/AttributesAPI/src/org/gephi/data/attributes/type/IntervalTree.java
@@ -132,8 +132,12 @@ private void insert(Node z) {
 				x = x.left;
 			else x = x.right;
 			y.max = Math.max(z.max, y.max);
+			if (y.p == root)
+				root.max = y.max;
 		}
 		z.p = y;
+		if (y == root)
+			root.max = z.max;
 		if (y == root || compareLow(z.i, y.i))
 			y.left = z;
 		else y.right = z;
@@ -202,8 +206,11 @@ public void delete(Interval interval) {
 
 	private void delete(Node z) {
 		z.max = Double.NEGATIVE_INFINITY;
-		for (Node i = z.p; i != root; i = i.p)
+		for (Node i = z.p; i != root; i = i.p) {
 			i.max = Math.max(i.left.max, i.right.max);
+			if (i.p == root)
+				root.max = i.max;
+		}
 
 		Node y;
 		Node x;
@@ -307,6 +314,8 @@ private void leftRotate(Node x) {
 		y.left = x;
 		x.p    = y;
 
+		if (y.p == root)
+			root.max = x.max;
 		y.max = x.max;
 		x.max = Math.max(x.i.getHigh(), Math.max(x.left.max, x.right.max));
 	}
@@ -324,6 +333,8 @@ private void rightRotate(Node x) {
 		y.right = x;
 		x.p     = y;
 
+		if (y.p == root)
+			root.max = x.max;
 		y.max = x.max;
 		x.max = Math.max(x.i.getHigh(), Math.max(x.left.max, x.right.max));
 	}
diff --git a/AttributesAPI/test/unit/src/org/gephi/data/attributes/type/IntervalTreeTest.java b/AttributesAPI/test/unit/src/org/gephi/data/attributes/type/IntervalTreeTest.java
new file mode 100644
index 000000000..2cae897c4
--- /dev/null
+++ b/AttributesAPI/test/unit/src/org/gephi/data/attributes/type/IntervalTreeTest.java
@@ -0,0 +1,96 @@
+/*
+Copyright 2008-2010 Gephi
+Authors : Cezary Bartosiak
+Website : http://www.gephi.org
+
+This file is part of Gephi.
+
+DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+
+Copyright 2011 Gephi Consortium. All rights reserved.
+
+The contents of this file are subject to the terms of either the GNU
+General Public License Version 3 only ("GPL") or the Common
+Development and Distribution License("CDDL") (collectively, the
+"License"). You may not use this file except in compliance with the
+License. You can obtain a copy of the License at
+http://gephi.org/about/legal/license-notice/
+or /cddl-1.0.txt and /gpl-3.0.txt. See the License for the
+specific language governing permissions and limitations under the
+License.  When distributing the software, include this License Header
+Notice in each file and include the License files at
+/cddl-1.0.txt and /gpl-3.0.txt. If applicable, add the following below the
+License Header, with the fields enclosed by brackets [] replaced by
+your own identifying information:
+"Portions Copyrighted [year] [name of copyright owner]"
+
+If you wish your version of this file to be governed by only the CDDL
+or only the GPL Version 3, indicate your decision by adding
+"[Contributor] elects to include this software in this distribution
+under the [CDDL or GPL Version 3] license." If you do not indicate a
+single choice of license, a recipient has the option to distribute
+your version of this file under either the CDDL, the GPL Version 3 or
+to extend the choice of license to its licensees as provided above.
+However, if you add GPL Version 3 code and therefore, elected the GPL
+Version 3 license, then the option applies only if the new code is
+made subject to such option by the copyright holder.
+
+Contributor(s):
+
+Portions Copyrighted 2011 Gephi Consortium.
+*/
+package org.gephi.data.attributes.type;
+
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.After;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+/**
+ * Unit test for IntervalTree class.
+ *
+ * @author Cezary Bartosiak
+ */
+public class IntervalTreeTest {
+	public IntervalTreeTest() { }
+
+	@BeforeClass
+	public static void setUpClass() throws Exception { }
+
+	@AfterClass
+	public static void tearDownClass() throws Exception { }
+	
+	@Before
+	public void setUp() { }
+	
+	@After
+	public void tearDown() { }
+
+	@Test
+	public void testClass() {
+		System.out.println("Class");
+		
+		IntervalTree<Integer> itree = new IntervalTree<Integer>();
+        itree.insert(new Interval<Integer>(1.0, 1.0));
+        itree.insert(new Interval<Integer>(5.0, 5.0));
+        itree.insert(new Interval<Integer>(7.0, 7.0));
+        itree.delete(new Interval<Integer>(5.0, 5.0));
+        itree.insert(new Interval<Integer>(5.0, 6.0));
+        itree.delete(new Interval<Integer>(5.0, 7.0));
+        itree.insert(new Interval<Integer>(5.0, 7.0));
+        itree.delete(new Interval<Integer>(1.0, 1.0));
+        itree.insert(new Interval<Integer>(1.0, 2.0));
+        itree.delete(new Interval<Integer>(1.0, 2.0));
+        itree.insert(new Interval<Integer>(1.0, 2.0));
+		List<Interval<Integer>> list = new ArrayList<Interval<Integer>>();
+		list.add(new Interval<Integer>(5.0, 7.0));
+		assertEquals(itree.search(4.0, 5.0), list);
+        System.out.println("itree.search(4.0, 5.0): " + itree.search(4.0, 5.0));
+		System.out.println("list: " + list);
+		System.out.println();
+	}
+}