differential equations – How to solve NDSolve dependent on two NIntegrates?

 Kab(n_, z_) := NIntegrate((1 + (t*n)/(f0(z))^2), {t, 0, 1});
 S4(n_, z_) := NIntegrate((t/(n*(f0(z))^2)*Exp(-2*Kab(n, z)*z)), {t, 0, 1});
 Com(n_, z_) := NDSolve({(f0'(z)) == n*Exp(-2*Kab(n, z)*z)*S4(n, z), f0(0) == 1, f0'(0) == 0}, f0, {z, 0, 3});
  ca(n_, z_) = Com(2, z)
 Plot(Evaluate(f0(z) /. ca(n, z)), {z, 0, 3})

My code is given above. I am unable to get the plot and getting some errors.