Trouble adding an uncredited credit to The Castaway Cowboy (1974)

I tried to add an uncredited credit to The Castaway Cowboy in contribution #240211-155438-529000 but IMDb rejected this. The uncredited musician is: Louise Di Tullio musician: flute Here is the photo and reliable link of where I've found this: http://www.louiseditullio.com/Flute-Soundtracks.html