If the nuclei are reddish-brown in color rather than blue-purple they have not been sufficiently blued. Increase the time in the bluing reagent.
Or, the hematoxylin may be beyond its' expiration date and needs to be replenished with a new, fresh batch.
This top image is a slide that did NOT go through the bluing step.
The bottom image is a slide that has been properly blued.
