How can I get the dealer to honor my extended warranty?

More regarding this issue. When I purchased this used vehicle, I also purchased an extended maintenance warranty to cover drive train problems. I had new water pump, timing belt, radiator hoses, spark plugs, battery and transmission serviced. When this trans problem occurred, I took the car to Aamco for a complete analysis. Then I took it to the dealer where purchased. They said the engine light was not on and they couldn't have the warranty repair done unless they could prove to the warranty company that there was a real problem. I even gave the dealer a copy of the Aamco diagnosis. What could you suggest that I should do to have this repaired? I am running out of mileage and term time restrictions. The dealer suggested that I continue to drive it until the engine light comes on.