Not able to add Link Data without 'to' property gojs

Hi, I am not able to add Link Data using model.addLinkData function without ‘to’ property in it gojs
object is var linkdata{ from ‘key’, points : points_array}.
template is as follows:

var GO = go.GraphObject.make;  
                             routing: go.Link.AvoidsNodes,
                             selectable: true,
                             reshapable: true,
                             resizable: true,
                             relinkableTo: true,
                             curve: go.Link.JumpOver,
                             corner: 10
                      new go.Binding("points").makeTwoWay(),
                        { strokeWidth: 1.5 }, new go.Binding("scale", "scale", function (s) { 1 / myDiagram.scale }).makeTwoWay()),
                        { toArrow: "Standard", stroke: null })

have also enable:

"linkingTool.isUnconnectedLinkValid": true,
"relinkingTool.isUnconnectedLinkValid": true

That’s a good start, and it’s necessary if you want to allow users to draw such links.

Have you seen Draggable Link ?

Thanks. walter.