diff --git a/projects/Chart/22/org/jfree/data/KeyedObjects2D.java b/projects/Chart/22/org/jfree/data/KeyedObjects2D.java
index d0e832f..7cc5ad6 100644
--- a/projects/Chart/22/org/jfree/data/KeyedObjects2D.java
+++ b/projects/Chart/22/org/jfree/data/KeyedObjects2D.java
@@ -228,9 +228,10 @@ public Object getObject(Comparable rowKey, Comparable columnKey) {
             throw new UnknownKeyException("Column key (" + columnKey 
                     + ") not recognised.");
         }
-        if (row >= 0) {
         KeyedObjects rowData = (KeyedObjects) this.rows.get(row);
-            return rowData.getObject(columnKey);
+        int index = rowData.getIndex(columnKey);
+        if (index >= 0) {
+            return rowData.getObject(index);
         }
         else {
             return null;
@@ -315,8 +316,29 @@ public void removeObject(Comparable rowKey, Comparable columnKey) {
         }
         
         // 2. check whether the column is now empty.
+        allNull = true;
         
+        for (int item = 0, itemCount = this.rows.size(); item < itemCount; 
+             item++) {
+            row = (KeyedObjects) this.rows.get(item);
+            int columnIndex = row.getIndex(columnKey);
+            if (columnIndex >= 0 && row.getObject(columnIndex) != null) {
+                allNull = false;
+                break;
+            }
+        }
         
+        if (allNull) {
+            for (int item = 0, itemCount = this.rows.size(); item < itemCount; 
+                 item++) {
+                row = (KeyedObjects) this.rows.get(item);
+                int columnIndex = row.getIndex(columnKey);
+                if (columnIndex >= 0) {
+                    row.removeValue(columnIndex);
+                }
+            }
+            this.columnKeys.remove(columnKey);
+        }
     }
 
     /**
@@ -342,6 +364,10 @@ public void removeRow(int rowIndex) {
      */
     public void removeRow(Comparable rowKey) {
         int index = getRowIndex(rowKey);
+        if (index < 0) {
+            throw new UnknownKeyException("Row key (" + rowKey 
+                    + ") not recognised.");
+        }
         removeRow(index);
     }
 
@@ -375,7 +401,10 @@ public void removeColumn(Comparable columnKey) {
         Iterator iterator = this.rows.iterator();
         while (iterator.hasNext()) {
             KeyedObjects rowData = (KeyedObjects) iterator.next();
-                rowData.removeValue(columnKey);
+            int i = rowData.getIndex(columnKey);
+            if (i >= 0) {
+                rowData.removeValue(i);
+            }
         }
         this.columnKeys.remove(columnKey);
     }