Is the type there really called sampleBase? That seems uncommon, most GraphQL types start with a big character. Can you show the schema you are working with?
I’m sorry, you need to be a lot more specific. After you corrected your fragment spelling there, what response do you get from the server, and what response do you expect?
Also, is SampleBase an interface, or a type? In the case of an interface, are you using possibleTypes?