Strike Up the Band
Starring Mickey Rooney, Judy Garland, June Preisser, William Tracy, Larry Nunn, Paul Whiteman, Margaret Early, Ann Shoemaker, Francis Pierlot, Virginia Brissac
It's a drama and musical movie, and has a rating of 6.8 out of 10 from Imdb which is usually fine for this kind of movie.
Watch it here
Not found streaming from Germany.