The story of Sixto Rodriguez, popularized in the documentary "Searching for Sugar Man", highlights what is frequently an issue for recording artists and songwriters: payment of royalties. Sometimes it's poor accounting by labels or publishers, sometimes malfeasance, and sometimes artists don't know who owns the rights to their music because the copyrights have changed hands so many times. Maintaining copies of contracts and records of payment are key to sorting out and resolving royalty underpayment!