The error is on the Channel Name field: "Roku requires that names for channels within the Channel Store are unique. The name you have selected for your channel is not available. Please select a different name."
I'm fairly certain that the name I'm using, "RockinShare" should be unique. We are a new startup and we own the domain and trademark for this. I've published a few private channels over the course of the last few months with RockinShare in the name.. but always something like "Rockin Alpha" etc.
Hopefully this is just a little database issue that can be fixed. I have deleted all my private channels if that helps.
FYI to anyone creating channels: Channel names must be unique, you cannot have a public channel and a private channel with exactly the same name. Roku Developer Support can resolve this situation for you by renaming the Private channel for you, as has been done in this case.