Node Link Text - Tooltip

Hi ,

how can i set tool tip on node link text (tooltip on node is working fine)

Sample code :

> {
> 	toolTip:
> 		goJ(go.Adornment, "Spot",
> 			{ background: "transparent" },
> 			goJ(go.Placeholder, { padding: 5 }),
> 			goJ(go.TextBlock,
> 				{ alignment: go.Spot.Top, alignmentFocus: go.Spot.Bottom, stroke: "red" },
> 				new go.Binding("text", "key", function(s) { return "key: " + s; }))
> 		)
> }

Not much help with : http://gojs.net/latest/intro/toolTips.html

Well, do your links have a “key” property on their data?

What is the problem? The Basic sample demonstrates tooltips on Nodes, Links, Groups, and on the diagram background.