There appears to be an error in this listing: The content listed under Opus 12 Op.12 - 2 Morceaux de salon, Violin and Piano (ca. 1845) 1.Ave Maria 2.Tonjours heureux really belongs under opus 16.
You can verify, because the score for Op.16 is in your database.
This work also needs an Ave Maria tab. avemariasongs.org
--Thank you for catching this. I have consulted the appropriate reference source and have verified your observation. I fixed the listing accordingly.