The element may only appear once in this section.

Question

Hi,
Could anybody help me regarding this. I have been working on this for a quite long time. but still i am recieving this same error. I have referred many sites but i could not found a solution.
Problem desc: I want to read the custom sections from the app.config. the entries are given below:
<configSections>                                                                       <section name="group" type="InScape.UI.CustomObjectsLib.GroupSection, CustomObjectsLib"/>                                                                 </configSections>
<group name="Group1">                                                         <permission name="Read" description=""/>                                           <permission name="Write" description=""/>                                     <permission name="Modify" description=""/>                                           </group>
Here i want to read the all permission element values inside a section 'group'.
Here are the classes declaration i have used..
public class GroupSection : ConfigurationSection   // Main class
public class PermissionElementCollection : ConfigurationElementCollection  // collection object
public class PermissionElement : ConfigurationElement  //element .. information