Can not create invitation code on CRM contact !

Hello Everyone,

I installed customer portal and after deploy the web site i need to test it by invite someone to register So,

When i try to generate an invitation code, nothing happen and an error appear:

Microsoft Dynamics CRM Error Report Contents

<CrmScriptErrorReport>
  <ReportVersion>1.0</ReportVersion>
  <ScriptErrorDetails>
   <Message>'CreateInvitationCode' is undefined</Message>

Can you help me !

Thanks