unable to go into include of userExit

Hello EveryBody,

I am new to userExits.i want to implement a function exits.for that i have created one project and i have assigned a component.in that component there are 3 functional exits.when i double click function exit it opens a function module where i have one include.

when i doublr click on include 'it is not going to editor' where i can implement functional exit.

and it is giving some messaeg like 'zx ..' is reservered for userexits.choose another name space.

what might be the problem

With regards

Naidu