ok, put it like this i have three similar clips (same effects, but different videos). The first two i can blend together with the additive dissolve transition, but the second and third I can't. When I try to put the transition between these clips, it doesn't come over the two clips i.e. the end of the second clip and beginning of the third like it should, but it stops at the end of the second clip. Why is this?
Well, one thing, you can't copy attributes then paste a transition out of the deal. You could paste a whole clip and get a transition, but that's not what you were looking for is it?
The process that you describe is hard to follow, like, it sounds like you stated that you nested 3 clips so you could use the additive dissolve to transition the 3 clip sequence into the next clip. So I'll assume you didn't mean that you had to create a 3 clip nested sequence to use the additive dissolve, and that the 3 clips sequence was incidental.
Where new users often trip up with transitions is not having enough pre and\or post roll on a clip or sequence to actually add the transition where they want it. Not enough footage in simple terms. I call it pre-roll-and post-roll from AB roll tape to tape editing, others call it heads and tales on a clip, or handles. Basically, there needs to be enough footage so that clip B begins with the first frame of the transition. With clip A there needs to be enough footage to reach the last frame of the transition.
Otherwise, what could be causing issues is the hard to predict visual results of an Additive Dissolve. I rarely use it, and often when I've looked at using it, I don't like the results
Well I found my problem. The additive dissolve transition or any transition that blends two clips, usuallly requires extra footage as it blends over to the following footage. Since I nested the clips together, and didn't have any extra footage at the end of the sequence to transition over, the additive dissolve transition wasn't able to work. Therefore, in order for my problem to be fixed, I need to make the nested sequence just a little bit longer, or just cut it shorter to make the transition work.
usuallly requires extra footage
Actually, it ALWAYS requires that extra footage. The industry term is "handles".
This is pretty well covered in the Help file.
Glad you worked that out for yourself.