Im trying to show the results of NdSolve by using Parametric Plot.These are pendulum equations and I want to get phase-space trajectories of this system. For small angles like Pi/5 i should get a circle.Here is my code
pend[\[Theta]0, \[Omega]0, \[Gamma], \[CurlyPhi]0, \[Omega]D, T] :=
NDSolve[{\[Theta]'[t] == \[Omega][t], \[Omega]'[
t] == -\[Gamma]\[Omega][t] -
Sin[\[Theta][t]] + \[CurlyPhi]0 Cos[\[Alpha][t]], \[Alpha]'[
t] == \[Omega]D, \[Theta][0] == \[Theta]0, \[Omega][
0] == \[Omega]0, \[Alpha][0] ==
0}, {\[Theta], \[Omega], \[Alpha]}, {t, 0, T}];
sol1 = pend[Pi/5, 0, 0, 0, 0, 100];
ParametricPlot[
Evaluate[{{\[Theta][t], \[Omega][t]} /. sol1}], {t, 0, 30},
PlotRange -> All, Frame -> True]
I keep getting the error message that the result of NDSolve " is neither a list of replacement rules nor a valid dispatch table, so cannot be used for replacing". I don't know how to fix it. I would appreciate your help very much.