Maven project: The hierarchy of the type SpittrWebAppInitializer is inconsistent

I am using eclipse to implement the codes in the book "Spring In Action".

package spittr.config;

import org.springframework.web.servlet.support.AbstractAotationConfigDispatcherServletInitializer;
import org.springframework.web.servlet.support.AbstractDispatcherServletInitializer;

public class SpittrWebAppInitializer extends AbstractAotationConfigDispatcherServletInitializer{

}

Then i have a error like this:

    "The hierarchy of the type SpittrWebAppInitializer is inconsistent"

But i have imported the necessary class in the library: Maven dependencies

Maven and SpringMVC is new to me and i'm confused about this error, please help me.