How to change a parameter of Proxy-Authorization header

Hello all,

I´m trying to change a specific part of the Proxy-Authorization but it does'nt work, the header look like this:

Proxy-Authorization: Digest username="12345678",realm="realm",nonce="87654321",uri="sip:55555555@172.191.10.2",response="1012ff724e36329461c4869",algorithm=MD5;

want to change uri="sip:55555555@172.191.10.2" for uri="sip:55555555@domain.com"

I´ve tried using the following header rule:

        header-rule

                name                                    chgProxyAuth

                header-name                             Proxy-Authorization

                action                                  manipulate

                element-rule

                        name                                    uri

                        parameter-name                   host

                        type                                    header-param

                        action                                  replace

                        new-value                            domain.com

Do you have any suggestion,

Thanks in advance.