how to use function getStart of the macro class Designer?

function information in ARIS help from macro class Designer: 

getStart ( Model model, Lane lane )

Determines the starting point (coordinate in X or Y direction) at which the transferred lane begins  

I am sure I am calling the method with a not empty lane and not empty model, but I still get an null point error.

  selection = Context.getSelectedModels(); //modelos selecionados

 if (selection.length > 0) {
        for (var i = 0; i < selection.length; i++) {
            var currentModel = selection[i];

  var modelLane = Designer.getHorizontalLanes(currentModel);
                
                
                for (var b = 0; b < modelLane.length; b++) {
                var currentLane = modelLane[b];     

 var getIn = Designer.getStart(currentModel, currentLane); //here is where I get the null point error.

Has someone used this function before? does it work properly or am I missing something here, I do this early in the code:

  var des = Designer.openModel(currentModel, false, false, false);
                var setVis = Designer.setVisible(currentModel, false);