[MidnightDraven]

ok, under the part where you put in which icons you want, click the button "reposition"
This will then highlight each bit, and you can see the highlight area. This whole area is the bit that may be crossing the banner or edges.

This pic shows the highlighted icons, and i have moved to it show that this would cause the error you are getting.
Even if it looks almost center and under the banner, just move it a bit and then export and see what it says.