ASM configurations advise

I just tried, The character ':' is not allowed for Server:ABC. I added Server to the Response Headers Allowed, but still cannot see the Server header in the response.

I did try added the iRule from the article https://support.f5.com/kb/en-us/solutions/public/10000/000/sol10089.html, but it added Xerver: ABC. I changed to Server instead but failed working.

when HTTP_RESPONSE { if { [HTTP::header exists "Server"] } { HTTP::header insert Xerver [HTTP::header value "Server"] } }