Object Error

Hi,
I am using following javascript to delete rows from a table. When I add a line to click a button with that it gives an error as 'Object Error'.
Can someone tell me why I get that error here and how can I solve it?
function deleteRow(tableID)
    {    
        try
        {
            var table = document.getElementById(tableID);
            var rowCount = table.rows.length;
            var btn = document.getElementById('btnDelete2');       
            btn.click();    
            for(var i=0; i<ro ...