We can't really tell you that because we don't know any specifics and from the sound of it, you don't either. Do you thoroughly review your verbal afterwards. It's seems strange that you can get a perfect score on a test in EK and less than 75% on AAMC. They're different but not THAT different. Look at why you are getting the EK questions right or wrong and why you are getting AAMCs and compare. Is the wording different? Is the passage style different? Is there a disparity of types of questions? Those are just some of the questions you should ask. I'm sure you can think of more. You should also be asking yourself questions about specific passages as you review. It's not enough to get questions right, you should know exactly why you got them right or wrong and what you could have done differently. Verbal is about finding angles to each question type and practicing until you perfect them. Each type of question needs to be answered differently and you need to review enough so you can walk away saying "Yea, I know exactly what that question was asking, how they wanted me to get the answer, and the ways in which I could have approached the questions better" If you can't answer those off of the top of your head then you're not reviewing your verbal correctly. If you can't verbalize or write those down then you're not reviewing enough. I remembered specifics for verbal days after I took them and sometimes more than a week. The specifics faded but the approach and how to go about answer the questions stayed.
It's about practice and thorough review. That's the definition of refining and that's exactly what you need to do with this test, refine your skills to the point that you don't have to rely on luck or easy verbal or anything else, just on your refined skills.
Hope this helps,
-LIS
