SERIAL NO ISSUE

I WANT TO ADD SERIAL NO IN A LIST PAGE, I HAVE DONE USING AN INTEGER VARIABLE AS SR NO AND CODE IS WRITTEN ON ONAFTERGETRECORD
SR NO:= SR N0 +1;
ITS WORKING
BUT NO CHANGES WHEN I DO EXPORT TO EXCEL USING CTRL+E OR BY CLICKING THE ASCENDING OR DESCENDING ARROW IN LIST PAGE. I M USING NAV 2013 R2

Hi Seemab,
Please use the NAV developer forum for NAV related questions. D365 forum for D365! Moved.
And please in the future, do NOT use write in UPPERCASE only. Thanks.