I have a very long form. Normally when I need to add a page in the middle, I right-click on the hierarchy, select "New Page" (it gets placed at the bottom), and I drag it up to where I want it in the list.
However this time it didn't work and I believe it was because I have a script object with a function at the highest level of the hierarchy. The new page was below {Variables}\scriptObject. Designer 8 wouldn't let me select the new page. The new page didn't even appear in the form (although it was listed in the hierarchy).
I had to save the file, close it, and then open it. Then the new page appeared. I was able to move it in the hierarchy and rename it.
The only difference now as opposed to all the other forms I have created is that this one had a function in the Variables section and the new page was listed below it.