Photoshop CS4 Color Issue?

My partner is coloring a picture on photoshop and whenever she uses the paint bucket to fill in a color, it changes the color to something else. For example, she was trying to fill something in with Navy blue, but it kept coming out black. And instead of getting a peach color it was more of a pastel yellow. We need to know how to fix this, because every other site I've gone to isn't much help.