Resource Load Prefab

I get the error:

ArgumentException: The prefab you want to instantiate is null. UnityEngine.Object.CheckNullArgument (System.Object arg, System.String message) (at C:/BuildAgent/work/b0bcff80449a48aa/Runtime/ExportGenerated/Editor/UnityEngineObject.cs:71) UnityEngine.Object.Instantiate (UnityEngine.Object original, Vector3 position, Quaternion rotation) (at C:/BuildAgent/work/b0bcff80449a48aa/Runtime/ExportGenerated/Editor/UnityEngineObject.cs:52) sCameraControls.Update () (at Assets/sCameraControls.js:100)

What I'm trying to do is store a list of prefab references in a class/struct and then use it as a master list when drawing the gui, spawning the objects, etc. I can't get Resource.Load to find the prefabs.

 class objectInfo extends System.ValueType {
     var name:String;
     var prefabName:Object;
 }
 var objectList = new objectInfo[3];
 var objectSelectionNew = 0;
 var objectSelectionOld = -1;
 var prefabPlacedObj:Object;
 
 function Start () {
 
     // define placeable objects
     var i=0;
     objectList[i].name = "default box";
     objectList[i].prefabName = Resources.Load("prefabCube");
     print(objectList[i].prefabName);
 
     i+=1;
     objectList[i].name = "default sphere";
     objectList[i].prefabName = Resources.Load("prefabCube2");
     print(objectList[i].prefabName);
 
     i+=1;
     objectList[i].name = "default cylinder";
     objectList[i].prefabName = Resources.Load("prefabCube3");
     print(objectList[i].prefabName);
 }
 
 function OnGUI() {
     // draw the onscreen gui
     
     // draw a list of placeable objects
     for(var i=0;i<objectList.length;i+=1) {
         if(GUI.Button(Rect(0,i*50,100,50),objectList[i].name)) {
             objectSelectionNew = i;
             //print("Clicked!");
         }
     }
     if(objectSelectionNew != objectSelectionOld) {
         objectSelectionOld = objectSelectionNew;
         prefabPlacedObj = objectList[objectSelectionNew].prefabName;
         print(prefabPlacedObj);
     }
 }