Select-Options Validation

I have selection option like the following

data : v_acti type char4
select-options: s_acti for v_acti obligatory.

Here user can enter value from 0000 to 9999

My requirement is to validate this Here user needs to allow values only from 2000 to 9999.

I have find following to do this :-->

(1). I have created a domain and put the value range as 2000 to 9999 and used that data element. ( This is not working and not giving error message if user enter value as 1000 in s_acti-low)

I know it can validated in "at selection screen" event . But the issue is here user can enter values <2000 or >9999 or ne 2000 like that . I find these combinations validations in the "at selection screen" more tedious.

Other possible way i saw is create an internal table with value ranging from 0000 to 1999 and value the selection option

s_acti as

loop at itab.
if itab-acti in s_acti.
  message e000(v1) with "Wrong Input"

But don't want above like

Finally my requirement is to make validation in at selection screen event if user values as < 2000 combination i have give an error message.

Moderators : please do not lock this thread i have searched this forum for nearest one answers, but could not find.