For historical bloggy reasons, the_date in WordPress won’t show the same date twice in a row. This is for grouping purposes.
The fix is easy: Use the_time instead. It behaves exactly the same as the_date, but without the internal historical logic. Also no need to rewrite any complicated code, just change three characters. 🙂
Note: the_time is missing the before, after, and echo parameters, but that’s okay because you really don’t need them. It always echo’s, and you can put the before and after parameters surrounding it quite easily. Like I said, there are historical reasons for the operational behavior of the_date, which don’t make sense except in specific circumstances which generally don’t apply anymore.