I have a full text catalog with two tables in it.
tableA has 4 columns (a1, a2, a3, a4) of wich 3 are indexed in the catalog, a2,a3,a4. a1 is the primary key.
t
Your query only returns records, if both A and related B contains the search text.
You do not state what does not work, though.
Why not LEFT OUTER JOIN the fulltext searches, and replace:
SELECT *, (ISNULL(ftTableA.[RANK], 0) + ISNULL(ftTableB.[RANK], 0)) AS total_rank
and
WHERE ftTableA.Key IS NOT NULL OR ftTableB.Key IS NOT NULL