Fétis produced a large quantity of original compositions, from the opera and the oratorio to the simple chanson, including several musical hoaxes, the most famous of which is the "Lute concerto by Valentin Strobel", premiered with Fernando Sor as soloist. Carcassi, as well as Sor, participated in the performance. The work is attributed NOT to the Alsascian lutenist Valentin Strobel, but to Jean (Johann) Strobach, a member of a prominent Bohemian family of musicians. This Strobach (fl. 1650-1720) served Leopold I, and there is no evidence that Fetis's score is a hoax. The composition was published in 1698, although no copy is known to have survived, except Fetis' manuscript score, which is in the Royal Conservatory Library in Brussels.