In late 1967 a band called "The Lemon Pipers" released a song titled "Green Tambourine". It was a massive hit, their only one, staying at the top of the charts seemingly forever. The "Lemon Pipers" were never heard from again. "The Turtles" had many hits, both before and after "She's My Girl".
Why is one song a hit and another doomed? No one knows.