Conditional if/elseif statement format?

I am working on a report that should show our product broken down into 1 of 3 buckets which I have labeled as 'Forecast Class'. I have created an If / Elseif conditional statement but I can't seem to get it to work properly.  I suspect it's because of the order I have it broken down? But i've tried it other ways and still can't seem to get it.

I'm including a picture which will show what my calculation is currently and the rules for the forecast class bucket.

Any help is greatly appreciated!