Wydom@ker, I think I know what the problem is, and I can understand your confusion if you had never played GC1.
After selecting the invation type and going to the next screen you get a screen that (some future beta if they carry this feature over from GC1) is a randomizer (if you watch long enough, you will see two numbers that change, from 2 to 1 to 3 to 2 to ....).
On GC1,
This screen includes the text to "Press the space bar". What this does is to lock in the variables at the time you press the space bar and procede with the invasion and to update the results as the invasion progresses. When the invasion is done the "done" button is activated.
On GC2,
This screen is missing the "Press the space bar" text. Clicking "done" is aborting the invasion. The space bar works at this level of the beta in GC2 just like it did in GC1.