I have not tested GraphWalker. My opinion about Concordion is positive, but Concordion is more technical compared to Cucumber. More technical is in some cases not positive. Especially the day when you get your product owner to write the features.
To be able to assist you I would need more information. such as the error you encountered. If I do some guessing I would ask, did you add the dependency in the right pom? There are more than one pom involved in this example. Double check where you have added the Cucumber-jvm references.