If I attempt to use any magic strings with curly brackets ({member.id}, {ghiaoghiaogh}) I get the following Exception on my page instead of the form:

System.Web.HttpException (0x80004005): Error executing child request for handler 'System.Web.Mvc.HttpHandlerUtil+ServerExecuteHttpHandlerAsyncWrapper'. ---> System.Exception: Exception while creating a value. ---> System.ArgumentException: An item with the same key has already been added.

The contents of the curly brackets don't seem to matter. It can be a form field alias, it can be nonsense. I get the same error every time.

Magic strings such as [#pageName] seem to work just fine.