SDP manipulation to Reject INVITE

I created this HMR to reject INVITE with 488 if SDP has T.38 offering, couldn't get to work any idea what's wrong with my logic ?

sip-manipulation

        name                                    SDPmanipulation

        description

        split-headers

        join-headers

        header-rule

                name                                    checkSDP

                header-name                             Content-Type

                action                                  manipulate

                comparison-type                         pattern-rule

                msg-type                                request

                methods                                 INVITE

                match-value

                new-value

                element-rule

                        name                                    rejectt38

                        parameter-name                          application/SDP

                        type                                    mime

                        action                                  reject

                        match-val-type                          any

                        comparison-type                         case-sensitive

                        match-value                             a=T38.*$

                        new-value                               488:NA

        last-modified-by                        admin@console

        last-modified-date                      2017-01-11 04:44:03