The ordering part of the solution is format sensitive. When the order statement is not formatted in the way it is in the solution, the test will give out an error even though it should execute without a problem.

Mybe that's just me but from the way the exercise is worded, I assumed it was expected to write a query that would ONLY insert the new row IF the participant was age 21 or older.
Another way to understand it would be that at any attempt that you try to add a particpant younger than 21 to the table, it would change the 'attending' column to False.

Both ways seem too hard for a Kyu 8 level, but well... the wording should really be reconsidered.

For my fellow strugglers: You need to first simply insert your row and then just print the table with the age-condition.