Hi,
yes, this is an important warning that you must correct.
basically, the proxy you dropped onto your gameobject doesn't find any UI components.
so, either, instead of "use owner" you choose "Specify GameObject" and drop the GameObject with your UI text component on it", or you add the UI Component proxy on the object that has this UI Text.
also, make sure you are using the proper UI Text from Unity new UI system and not something else, like a meshText, or GuiText etc.
Bye,
Jean