Dynamic Chart Question

[DoubleZ]

In Excel 2007 I have created a dynamic chart. The data is working out just
fine, however the horizontal axis labels are not correct. For instance, in
one case my x values are 5,6,7,8 but the horizontal axis shows 0,1,2,3,4,5.
When I right click on the graph and select 'Select Data' the 'Edit' box is
grayed and I cannot click on it.

How do I get the correct numbers on the horizontal axis?

Thanks,
DoubleZ