[users@httpd] header out working in local apache but not on development environment

[eeadev dev]

I used this apache C function

*        apr_table_addn(r->err_headers_out , "Remote-Proxy-User",
"UserUpn=ME");*
I can see the result in my chrome dev tool when I use it in an apache
running locally but It does not work in the development environment.
what could be the reason?
Thank you