Puzzled -- My laptop into the Aux imput on my Kn7000 -- I am using Line In for something else.

1-I can hear the music, and I understand there is no volume control for the Aux impute ---
2-The main outputs of the Kn7 go into my Mini Disk recorder.
3-When I play the keyboard, or sing--(mic is connected to the Kn7) I can recoard without problem.
4-Laptop into the aux impute can be heard but does not go to my Mini Disk recorder.

If I can hear my laptop --(no external amplication)-- and it will not record, where is the sound going--what output???

Thanks, John C.