Empty output from ParametricPlot

Hello, I am trying to plot the numerical values of f[y] on the horizontal axis and the analytical values of V[y] on the vertical axis. However, the ParametricPlot command is not giving me the graph. Could someone help me? Thank you very much.

Try f[y] /. First[s] instead of f[y] /. s. (The documentation shows this but does not explain it.)

thank you very much