error: invalid request handle

database: datenbanken\gartenhof-kuesters2.de\pictures.GDB
table: picture A join pictureobject B on A.object=B.id join picturetyp C on C.id=A.typ join zo_category_pictureobject D on D.pictureobject=B.id
sqlstring: Select count(DISTINCT A.id) from picture A join pictureobject B on A.object=B.id join picturetyp C on C.id=A.typ join zo_category_pictureobject D on D.pictureobject=B.id Where (D.category=161) and (A.object=5067)