My 1099-B doesn't have anything in Box 1b (Date Acquired). In TT, I selected the option that Box 1b is Blank, but I keep getting error msg "needs info". What do I put?

This 1099-B transaction involved the proceeds of about $20 from a stock distribution. (The company that I own some stock shares from an ESPP spun off another company for which I received cash in lieu of a very small fraction of shares.)