Color Objects
You may not be able to color some objects if you have colorable geometry on a layer above the other colorable geometry you are trying to apply a swatch to. It is important to remember that all colorable entities in Color exist on their own layers, and it is difficult to tell which layer is on top of the other as all entities are transparent until a color swatch is applied to it.
A simple technique when trying to apply a color swatch to an entity that you know should be colorable and yet does not highlight blue is to apply the swatch anyway, that way any items on a layer above it (the layer of the item you are trying to get at) will color in and become ‘visible’. You can then apply an appropriate swatch to the overlying layer and then send it to the background and then proceed to apply color swatches to the entities below.
You can find information with screen captures in the Color User Guide, a section entitled “Understanding the Layering Order” & “Helpful tips for the coloring process”.