I was referring to it being diatonically correct using Lydian in the diatonically correct IV position if...I know there isnt a D# in an AMaj7 chord....Not muddying any waters: Some folks play patterns......
I think the professor is looking for "correct" not "diatonically correct."
Like if you ask me to play "Mary Had a Little Lamb" and I play B A F G D D C, that is "diatonically correct" but certainly not "correct."
Just because a note fits the key signature doesn't make it the "right" note. Use your ears!!