F5 IRULE TO block exchange with external IP and useragent

I'm trying to block all non RFC1918 addresss when they use a particular useragent

when HTTP_REQUEST priority 1000 {

if { [matchclass [IP::client_addr] equals outlook_private_block] } { switch -glob [HTTP::header User-Agent] { "Microsoft Outlook" - "Microsoft Office" - "Microsoft Office/15.0 (Windows NT 6.1; Microsoft Outlook 15.0.4701; Pro)" - "Microsoft Office/15.0*" { log local0.info "Client IP:[IP::client_addr] has been blocked with user agent :[HTTP::header User-Agent]"

                     discard
            }
            default {
                    log local0.debug "Client IP:[IP::client_addr] attempt with user agent :[HTTP::header User-Agent] successful"
            }


    }

} }

I have tried to set the useragent to lower and match the variables with the lower strings but it does not work

I noticed it I remove the useragent string portion of it, the block works via the IP addresses. I'm not 100 percent sure why, but I'm doing something wrong.

I;m running 11.5.1

Any help would be appreciated