Click the Dependency Link button 
on the diagram toolbar.
Click the source element.
Drag the link to the destination element.
Drop when the destination element is highlighted.
You can draw a dependency link between any two elements.
To create a dependency link:
Click the Dependency Link button
on the diagram toolbar.
Click the source element.
Drag the link to the destination element.
Drop when the destination element is highlighted.
Related Topics:
Creating Links
Moving Links
Editing Links