I have plotted a line that represents a mean species diversity estimate (Y axis is species count, X axis is individuals collected). I have the upper and lower bound confidence interval data that I would like to add to the line graph.

But, when I try to add the mean, upper bound and lower bound lines to the Y axis it ALWAYS gives me an index for the X axis (as if the x axis is not the same for all of them... they do vary a bit but they are very close). I could use some advice on how to produce the three lines together in SPSS v21.