A family of Microsoft relational database management systems designed for ease of use.
Hey Alan, just happened to be sat in front of a Visio 2013 version so thought I'd test your work around. Unfortunately this doesn't appear to work for myself. Interesting that 'Apply' is enabled on your screen shot, with the issue it isn't enabled and you have to press 'OK', which then brings up the error message.
Cheers Aaron...