It’s bad enough that you were too lazy to change the default control names. Using “RequiredFieldValidator1” and “TextBox1” does not make your code easier to read.
None of the calendars are renamed from the default name, except for one that is enigmatically called “sixth”. “Sixth” is actually the 5th calendar in that section, and the 8th one overall.
But what’s really irritating is that RequiredFieldValidator4 doesn’t validate TextBox4, it validates TextBox1. None of the other validator names correspond with any other control names either. Why?
Yes, I hate you.