I am not able to follow what you are attempting to do. But to find why a plot comes out empty, it is always good idea to look at the data itself you are trying to plot using the Table command and see what is the problem. For example,
data = N@Table[{Cot[t]^2, Cot[t]}, {t, 0, 2 Pi, Pi/10}]
Thank you very much for your help this Nasser it is the graph that he hopes to obtain, also thanks for your council to tabulate I bear it very in mind it might be said that I already did mine.