"Object invalid" error for layer visible

Hi All,

I am getting the "Object invalid" error message for below code. please check and suggest me, where is error occurred in my code.

var myDoc =  app.activeDocument;

var myLayer = myDoc.layers;

for(var i  = 0; i < myLayer.length; i++)

  { 

      if(myLayer.name == "WEBPDF" && myLayer.visible == true)

        {  

            try

            {

                    myDoc.revert();

                    myLayer.visible = false;

                    myDoc.save();

                }

            catch(e){

                    alert(e);

                }

            }

      }