Haproxy ACL for query-string "Authorization"

Question

I am trying to create ACL in Haproxy to query Authorization from request header and route to backend based on AccessID. I have used map file which are populated with AccessID and backend server. I am sure that my ACL is not working and hence I am getting 503 for incoming requests. Any help is appreciated!

Config File:

frontend  main
        bind *:80
        capture request header Authorization len 50
        acl GET_calls method GET HEAD OPTIONS
        acl PUT_calls method PUT

       use_backend %[urlp,map_sub(/etc/haproxy/PUT_Header.map)] if PUT_calls

Map File:

# AccessID  backend server
JMYQ        get_s1
P2BH        get_s1
WEA1        get_s2

I have captured the request header in log and I see AccessID.

Apr  8 10:10:29 localhost haproxy[79517]: 0.11.4.1:929 [08/Apr/2022:10:10:29.232] main main/<NOSRV> -1/-1/-1/-1/0 503 212 - - SC-- 0/0/0/0/0 0/0 {Credential=WEA1} "PUT /common/Demo2.file HTTP/1.1"