Did you resolve this yet? When a "lookup" is used in a stylesheet, it has to be resolved somewhere up the ancestor chain of the node that uses the style. If the real value isn't found, then this message spits out. So the question is, why isn't the value found? It could be that it just isn't in a style that matches any of the node's parents. If you have it in the .root rule, then it should be found. The other possibility is that you are dealing with a popup. A popup gets its styles from the owner scene, but a popup doesn't have an owner scene until it is shown. There is also an issue where inline and parent styles don't convey to a popup.