Hi.
Try this: reduce brightness/backlight to 50% and calibrate again (don't use the ambiente light compensation setting). If it doesn't work, try this: calibrate using native white point, but with gamma 2.2.
Most monitors are already calibrated at 6500K, so correcting the gamma (on individual channels) works just fine.
Please let me know if this helps.
BTW, what's the monitor model?
Regards,
Luis