Hi all, I am quite new to Mathematica and have no idea what is wrong with my code. The code looks like the following:

m = 1
L = 1
a = Pi/4
o = 10
s = NDSolve[{m*r''[t] == -m*9.81*Cos[a]*Sin[a] + 
     L^2/(m*r[t]^3)*Power[Sin[a], 2], r[0] == 2, r'[0] == 0}, 
  r, {t, 0, o}]
n = NDSolve[{m*Evaluate[r[t] /. s]*p'[t] == L, p[0] == 0}, 
  p, {t, 0, o}]
ParametricPlot3D[{Evaluate[r[t] /. s]*Cos[Evaluate[p[t] /. n]], 
  Evaluate[r[t] /. s]*Sin[Evaluate[p[t] /. n]], 
  Evaluate[r[t] /. s]*Cot[a]}, {t, 0, o}, PlotRange -> Full]
Plot[Evaluate[r[t] /. s]*Cos[Evaluate[p[t] /. n]], {t, 0, o}, 
 PlotRange -> All]
Plot[Evaluate[r[t] /. s]*Sin[Evaluate[p[t] /. n]], {t, 0, o}, 
 PlotRange -> All]
Plot[Evaluate[r[t] /. s]*Cot[a], {t, 0, o}, PlotRange -> All]
Plot[Evaluate[r[t] /. s], {t, 0, o}, PlotRange -> All]
Plot[Evaluate[p[t] /. n], {t, 0, o}, PlotRange -> All]

The code solves my DGL and plots the result. The last two plot function show the parameters r and p. The three lines above show the components from the parametric plot. The plots look like expected, but when combining them, the parametric plot is empty. Does anyone know why? Thank you very much!