Why won't Pro Sites install on a valid multi-site install?

1. It won’t download/install from the WPMU Dev Dashboard. After manually downloading from the WPMU Dev site and manually uploading via the WP Dashboard it fails to install with this error:

Downloading install package from https://premium.wpmudev.org/wdp-un.php?action=install&key=3805234fea1304d02d82f75fa579ee898ffb1ff4&pid=49…

Unpacking the package…

Installing the plugin…

The package could not be installed. No valid plugins were found.

Plugin install failed.

Also fails to install Multidomain plugin with this error:

The uploaded file could not be moved to /home/public_html/wp-content/uploads/2013/06.

WP 3.5.1 with Multisite correctly configured.