# Plotting error for parametric plot

I am getting the following error when trying to use parametric_plot:

verbose 0 (3757: plot.py, generate_plot_points) WARNING: When plotting, failed to evaluate function at 200 points. verbose 0 (3757: plot.py, generate_plot_points) Last error message: ''Graphics' object is not callable'

Below is the code. Any ideas how I can avoid this?

t = var('t'); mu_E = 3.98601e5 #Mu in non-canonical km^3 s^-2 R_E = 6378.135; #Earth radius in km C_alt = 600; #Chief's altitude in km R_c = C_alt + R_E; #Orbit radius of chief

x0 = 69.78; y0 = 139.56; zo = 139.56; x0_dot = 0.; y0_dot = -151.116e-3; #in km/s z0_dot = 0.;

n = sqrt(mu_E/R_c^3);
T_c = 2*pii*sqrt((R_c^3)/mu_E); #Oribital period of chief

x(t) = (4*x0 +2*y0_dot/n) + (x0_dot/n)*sin(n*t) - (3*x0 + 2*y0_dot/n)*cos(n*t);
y(t) = -(6*n*x0 + 3*y0_dot)*t + (y0 - 2*x0_dot/n) + (6*x0 + 4*y0_dot/n)*sin(n*t) + (2*x0_dot/n)*cos(n*t);
px = plot(x,(0., 2*T_c)); #
py = plot(y,(0., 2*T_c)); #
pp = parametric_plot((px, py),(0, 2000),color=hue(0.6));