How to use the method SetValue() of ILayer

 

Now I have a imageLabel point layer, I want to use ILayer.SetValue() method to classify the attribute of scale according to point layer attribute.

 

Following is my code(in javascript):

 

var itemId = IInformationTree.FindItem("mk_pt.shp");
  var classStr = "<Classification><Class>" +
                 "<Condition><#text>\"[Text]\"=\"testString\"</#text></Condition>" +
                 "<Value><#text>100</#text></Value>" +
                 "</Class>" + "<DefaultValue><#text>0</#text></DefaultValue>"  +
                 "</Classification>";
  IInformationTree.GetLayer(itemId).SetFeature();
  IInformationTree.GetLayer(itemId).SetValue("Scale",1,classStr);

 

But there is an error, which is "A name was started with an invalid charactor". WHY?