Importing XML termbase with xcd as definition file?

Hello

I am a newbie starting work on my first translation project using Studio 2017. My client has sent me a termbase in XML format and, when I asked for the definition file, they provided an xcd file. I have tried creating a new termbase using the xcd file as a template and then importing the xml termbase but the result is a grand total of 0 terms! Is the xcd file the wrong thing for this? Any help will be gratefully received.