send object in sendMessage

I want to send a gameObject to another object. I'm getting some weird behaviour when I try to access the name of the object after passing it. See code below. The Debug.Log in Cube will print the name of the object. The Debug.Log in Main Camera will give an error: Assets/MainCameraScript.js(12,30): BCE0019: 'name' is not a member of 'Object'.

What gives? How do I pass an object to another script and access it's name?

 //this script is on 'Cube' in CubeScript
 function OnMouseDown()
 {
     Debug.Log(this.gameObject.name);
 
     GameObject.Find("Main Camera").SendMessage("PrintName", this.gameObject);
 }
 
 //this script is on the 'Main Camera' in MainCameraScript
 function PrintName (obj) 
 {
      Debug.Log(obj.name);
 }