HMR to remove part of User-to User info

I am trying to remove $Expires=.  from a To: message

To: <sip:+17872345676@10.161.200.120;user=phone;User-to-User=00C80A35313837373436343936%3Bencoding%3Dhex&Expires=2>, using something like this:

header-rule
                name                           removeExpires
                header-name                    To
                action                         manipulate
                comparison-type                case-sensitive
                msg-type                       any
                methods                        
                match-value                    
                new-value
                element-rule
                        name                           removeUUIexpires
                        parameter-name                 User-to-User
                        type                           uri-param
                        action                         delete-element
                        match-val-type                 any
                        comparison-type                case-sensitive
                        match-value                       &Expires=.
                        new-value

 

however it doesn't remove the Expires, if I change match-value to "" it removes the whole user-to-user part.