A 0 means that the cell in the array that you are referencing is empty, or not in the array. For example if the array is 10 wide, the only the indexes from 0-9 will have data, since they start at 0. So if you try to get the content at x=10, the result will be 0.
Without seeing how you have it set up I wouldn't be able to say why your dialogue events are showing 0.