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