Hi Don,
The most recent El Capitan installers contain a change which render them incompatible with Fusion. We didn't have the time to correct it before Fusion 8 shipped. For a workaround, see this post (which is now stickied at the top of the whole Fusion forum): Checking out El Capitan GM Candidate on Fusion 8 | mikeroySoft.com
Cheers,
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Darius