header out working in local apache but not on development environment

[eeadev dev <eeadev@xxxxxxxxx>]

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