Get count of distinct values based on a output field

Hi!

I am trying to get the count of similar items of a field in an internal table and put it in the counter column. I ahve the following code below but the result always shows zero in the entire column. Would really appreciate if someone can pls help me out on this.

What I want the output to show is :

Name  Address  Counter

A             A01       

B             A01        02

C             B01

D            B01

E             B01        03

F             C01

G            C01        02

H            D01        01

SORT c_t_data BY build.

DATA : lv_build
TYPE build,

c_t_data1 TYPE TABLE OF ptdw_times WITH HEADER LINE,

wa_data1 TYPE ptdw_times,

v_flg TYPE c.

c_t_data1[] = c_t_data[].

LOOP AT c_t_data1 INTO wa_data1.

AT NEW build.

counter = counter
+ 1.

ENDAT.

AT END OF build.

wa_data1-counter
= counter.

ENDAT.

ENDLOOP.

c_t_data[] = c_t_data1[].

ENDFORM. "execute_user_exit

Thanks