How to move a pageItem is in overset

Hi All,

     The below code is execute proberly when it is not in overset. But if it is in overset it throws error.

MyXMLElement.select();

app.menuActions.itemByID(78629).invoke();                    //Go to Item

var grp = app.selection[0].parentTextFrames[0];

grp.select();

if(grp.parent.constructor.name != "Character"){     //to avoid anchor item

     while(grp.parent.constructor.name != "Page"){

          grp = grp.parent;

     }

     grp.move(app.activeDocument.pages[-1]);     //move last page

}

"grp.select()" throws error. How can I move the group item to last page.

Thanks in Advance,

Mahesh