What is wrong in here, please help:

dustplot0:=(points)->odeplot(duffing, [x(t),y(t)], 0..(2*Pi*points), numpoints=points);
plot1 := dustplot0(100):
plot1;

plot2:=PLOT(POINTS(op(op(1,op(plot1))),COLOUR(RGB, 0, 0.2,0.5),SYMBOL(POINT))):
plot2;
Error, invalid input: op expects 1 or 2 arguments, but received 3

I do not understand the reason for this error.

Thanks