She probably just didn't update an older ad. Or sometimes they will list dates as a way to drum up interest, but won't come if she's not booked ahead.
You didn't get a response because instead of just seeing her tourdates and asking about booking when she's there, you "asked for clarification" about the difference between two ads. That makes you look too paranoid to be reliable, she doesn't want to waste her time assuaging your fears.
Pick an ad, take it at face value. Tell her which ad you saw, then proceed to use that information about availability, rates, etc. If there is a contradiction with what you're trying to book, she'll tell you.