NullReferenceException: Object reference not set to an instance of an object

 

 I'm trying to fill the Dropdown list from data base for editing,textbox is fill properly but  error occured while trying to fill Dropdaownlist

I'm getting error here "DDL_Dept.Items.FindByText(e.Item.Cells[5].Text.ToString()).Selected = true;"
protected void DG_ItemCommand(object source, DataGridCommandEventArgs e)
{
if (e.CommandName == "Edit" ...