Problem of customer_add_data implementation

Hi Experts,

I am quite new to BADI. I am trying to implement the Customer_Add_Data to add custom fields to Customer Master (XD01). I have done below steps following a struction from SDN:

1. Create a customer screen group Z1 with one new tab label (1, Z1_TAB).

2. Create an implementation of Customer_Add_Data and activated it. Put below codes on the method "Check_ADD_ON_Active"

if i_screen_group = 'Z1'.

e_add_on_active = 'X'.

endif.

3. Create an implementation of Customer_add_data_cs. etc.

But I am not so lucky to see a new button appeared on the top of XD01 screen. How can I let this button visible? Any more steps I need to do for that?

Thanks in advance.

Yu