AXT-Application Enhancement Tool

Hi

I tried to create a business role for application enhancement tool referring the below link

http://scn.sap.com/community/crm/blog/2012/05/03/how-to-configure-application-enhancement-tool-aet-in-the-navigation-bar

I got the error 'Role SAP_AXT_EXTENSIBILITY_ADMIN' does not exist. Can anyone tell me how to solve this problem.

Regards

Geeth