Always Exclude value from variable input, ls_range-sign = 'E' not working

Hi, I'm trying to wrote a small abap code to always exclude values from variable input. The variable type I created is customer exit with selection option, Optional and Ready to input ticketed. And the varaible restriction is in the global filters.

The below is the code i worte in CMOD but it is working as Include not as exclude. Could anyone please help. Many Thanks

when 'ZRING_EXE_CE'.

if i_step = 2.

read table i_t_var_range into ls_var with key vnam = 'ZRING_EXE_CE'.

if ls_var-low NE ' '.

loop at i_t_var_range into ls_var where vnam = 'ZRING_EXE_CE'.

ls_range-low = ls_var-low.

ls_range-sign = 'E'.

ls_range-opt = 'EQ'.

append ls_range to e_t_range.

endloop.

endif.

clear ls_var.

endif.