You use the anchor tool in the Stroke Definition mode of Microsoft Expression Design. When you do this, no anchor points are available to drop or to select when you use the anchor tool.
This problem occurs because the anchor tool does not work correctly in some scenarios. This is a known problem that will be reviewed for a fix in a future version of Expression Design.
To work around this problem, right-click the artboard to see the anchor points, to apply the anchor points, or to change the anchor points.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.