Long dissolves

How do I create an ultra long dissolve? For example, I enter a duration of 30 seconds. I select the dissolve transition and set the time for 28 seconds. The dissolve only seems to be taking place over a period of 1-2 seconds, no matter what I enter as a duration value.

If I understand your question correctly, I was able to make a test and get a long dissolve. The slide you are dissolving to should have at least ONE second difference, E.G. make the receiving slide 31 seconds and the dissolve 30 secs.