Like most, my immediate boss is my admin/principal of the building. However, if I have an issue with my admins I start climbing the tree. That would then mean reaching out to my nursing supervisor and then executive director of nurses. While my admins are my boss they don't have a real clue what nurses do, if you are having issues you might need to have a chit chat with some folks. That doesn't always guarantee a fix but at least you are letting your principal know and that might involve climbing the tree.
I am also lucky that my admins in my buildings (I have 2) are great! I have had to reach out to my "bosses" in the operational offices this year but it was not because of an direct issue with the admins.