Complex sentence: At first, MGM chief Louis B. Mayer is not impressed with Judy's rendition of Zing Went The Strings of My Heart, but when Judy sings a different song an impressed Mayer says Little girl.
Split into simpler sentences: At first, MGM chief Louis B. Mayer is not impressed with Judy's rendition of Zing! Went the Strings of my Heart, but when Judy sings a different song an impressed Mayer says Little girl.