REST Sender adaptor matching rule error

Hi,

I have a REST Sender Channel where I changed the endpoint from /probation/end to /probation/end/pernr i.e.

I also adjusted the the endpoint in the Soapui test tool i.e.

For some reason I am getting an error when I execute this i.e.

Can anyone tell me why the first endpoint "/probation/end" worked, but the new endpoint "/probation/end/pernr" does not? Surely as long as it is in the REST Sender definition (screenshot 1 above), and in the SoapUI test tool resource (screenshot 2 above) then it doesn't make any difference what it is called?