log log plot of Solubility

We have a question for our analytical chemistry course. We are required to graph the solubilities of a general solution of X- and M+ using a log log plot. We can get the graph to form for around the forth region, but it will not graph in region A, B, or C of the plot. We must plot the mono, di, tri, and tetra complexes, as well as the mass balance, solubility, and Charge balance equations. We are thinking that this is a formatting error, but we cannot find a solution to our problem. If anyone can help that would be great! Thanks, Karen