Uneven grid spacing help

Hello All,

I was able to create an uneven grid that steps down, but when I go to change the number of bars in the X and Z axis I encounter a problem with the grid becoming deformed. When I go smaller than 10, parts of the grid extend past the perimeter, I highlighted where the issue occurs in blue. Also when I go larger than 10 the grid does not extend but its points do. If anyone could help with it would be greatly appreciated!

Thanks,

Andrew