This line:
"although it must be understood that this is comparing when a value in A1 equals X and the value in B2 is greater than 4. However, this formula is not valid"

Is unclear when you reach the "However,". The previous line is in fact valid, but you were refering to the next example.

If you could give it a new line it might help because I was confused until I read the next example.

Also great guide so far. Onwards to Lesson3!