Yu-Gi-Oh The Duelists of the Roses for PlayStation 2 how do you win?

I am on the land place were you vs Pegasus I have beat like 4 time already but for some resign when I try to go to the next lane place to duel Ishizu it keep saying you need to Exceed DC Level what does it mean and how do I get to duel her? And when I try to vs someone else it does the same thing and said need to Exceed DC Level! Can some 1 please tell me how to get past this so I can get to vs. the next duelist please?