(edited to focus the question)
I have two stage common source amplifier and I have trouble connecting the two stage with an intervening capacitor. (here https://docs.google.com/open?id=0BwG45lg3wcwnNWRXUlV6RVdkNU0
I have trouble adding a capacitor in the middle of the two stages (between the drain of stage 1 and the gate of stage 2). I get an error saying that there is a "floating node". What is up with that ? I do have a small AC signal of frequency 5K and amplitude 1 mv going through so it should not give me this error right?