FlexPro cannot stack X axes of a diagram like it can Y axes, but you can obtain the same effect by doing the following:
1.If the diagram does not have two X axes, first add an axis.
2.Double-click on the diagram's first X axis.
3.In the axis Properties dialog box, click on the Position tab.
4.In the Start of axis field, enter 0% and in the End of axis field, enter 50%.
5.Click on OK to close the dialog box.
6.Double-click on the second axis and switch again to the Position tab.
7.In the Position field, select the same position that you used for the first axis.
8.In the Spacing to the previous axis field, enter 0.
9.In the Start of axis field, enter 50% and in the End of axis field, enter 100%.
10.Switch to the Appearance tab and make sure that the option Account for this axis when drawing the grid is checked.