Azure Websites WebMatrix Add Existing File Greyed
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I have a dotnet nuke website hosted on the new Azure Websites Preview. I want to add a new logo image. I clicked the WebMatrix Icon and WebMatrix 2.0 was installed. I can see a list of my websites files in a tree view down the left side. I navigate to the images folder. I want to click the "Add Existing" icon from the "Files" section of the top ribbon menu but it's greyed out. Can anyone please advise why?