Invalid column name 'ISBN'

Invalid column name 'ISBN'

Ive created an update command but it has an error. My code is this.
cmd.CommandText = ("UPDATE Penalty SET [Due Date] = '"+ duedate +"' WHERE
ISBN = '" + textBox4.Text + "'");
cmd.ExecuteNonQuery();
it said that Invalid column name 'ISBN' . I cant figure out the error.