The OR condition, as written, will be met by any value in E2. Think about
it... any value in E2 that is not "Not-applicable" will meet the first
condition and, since this is an OR, the OR function will evaluate to TRUE.
On the other hand, if E2 does equal "Not-applicable", then the second part
of the OR condition will be true and, again, since this is an OR, the OR
function will evaluate to TRUE.
I'm kind of thinking your first expression is what you wanted, just
straighten out the parentheses as Dave and Max showed you.