HMR to add Accept-Contact header if its missing

Greetings,

 

Working on an HMR which does following;

 

1. Check for Accept-contact header, if MESSAGE already has Accept-Contact header then do nothing

2. If Accept-contact header is missing then add the header with "require;explicit" value

 

This HMR is adding one more Accept-Contact header if there is already one exist; can you please walk me thorugh what is wrong with the logic ?

 

 

sip-manipulation
        name                           addacceptcontact
        description                    addaccept-contactheaderifmissing
        split-headers                  
        join-headers