getParamForDisplayName("Source Text") and getValue() and setValue() are not working in component obj

[mspolater]

I have three diffucility in my code.

Firstly

textObjComponent.properties.getParamForDisplayName("Source Text")

 is returns "Failed to retrieve variables. Details: Error processing request: XML error in line 1

- Not well-formed (invalid token)"

Secondly my text component has a "Customer Name" text but this code

textObjComponents[4].properties.getParamForDisplayName("Source Text").getValue()

 returns "Ũ" I dont know what is this.

Thirdly

When I run this code 

textObjComponents[4].properties.getParamForDisplayName("Source Text").setValue("aaa")​

in Premiere Pro component instanceName and display text is gone and I can not understand what is the problem.

my full code is this:

var projectPath="my_path";
if (app.isDocument(projectPath)) {

    app.openDocument(projectPath);
    var project = app.project;
    var tracks=app.project.activeSequence.videoTracks;

    var textObj=null;
    breakFlag=false;

    for (var i=0, len=tracks.length; i < len ; i++) {
     
      clips=tracks[i].clips;
     
      for (var j=0, len=clips.length; j < len ; j++) {
        var clipObjectName=clips[j].name;
        if(clipObjectName=="texts"){
          textObj=clips[j];
          breakFlag=true;
          break;
        }
      }
      if(breakFlag){
        break
      }
     
    };
   
    textObjComponents=textObj.components;
    for (var i=0, len=textObjComponents.length; i < len ; i++) {

        textObjComponent=textObjComponents[i];
        if (textObjComponent.displayName=="Text"){
          3+5;
        }
    }
} else {
  alert(projectPath+" This document cant open.");
}

[mspolater]

it is debugging screenshot.