premise: Terry and Julian is a British sitcom that aired on Channel 4 in 1992. Starring Julian Clary, it was written by Clary, Paul Merton and John Henderson. The title is a spoof the title of the long-running BBC sitcom "Terry and June", whose star June Whitfield made a guest appearance in one episode of "Terry and Julian".
hypothesis: "Terry and Julian" writer Paul Merton hasn't written anything aired on the BBC.
reason: The text makes no mention of anything else Paul Merton has written.  And since Terry and Julian, the one thing we know he's written, was on Channel 4, we don't know for sure he's written anything on BBC.  Thus, the statement could be either correct or incorrect--we don't know.  As for why the system didn't get it right, it seems to have confused the fact that Terry and June was on the BBC and thinks the other British show was on the BBC, too.  So maybe it can't understand the concept of different TV channels within the same country.