Cause

Two or more structure boxes with the same DT have the Main placement property.

Solution

1. In the Message management dialog, select the device tag assigned to the message.
2. Navigate consecutively via the menu items Go to (graphic) and Go to (2nd coordinate) of the popup menu to the corresponding structure boxes in the schematic.
3. When doing so, double-click the insertion point to call up the properties of the respective structure box.
4. Deselect the Main placement check box of all structure boxes except one, so that only one structure box has this property.
5. Confirm your entries.
6. Repeat this process for all other structure boxes.
7. If required, start a new check run.