combobox depend another combobox problem

Question

I wanna select from first combobox id of a train and in the second combobox give me the wagon that train has (number of a wagon ) I did a database: that first table stored the train id and the second table stored wagon id + id train foreign key i tried this code and its work but when i choose another id it doesn't change the wagon combobox result

 

What I have tried:

adapter = new SqlDataAdapter("select * from train", cn);
SqlCommand cmd = new SqlCommand("select * from train", cn);
cmd.Parameters.Clear();
adapter.Fill(ds, "train");
comboBox1.DataSource = ds.Tables["train"];
comboBox1.DisplayMember = "id";
comboBox1.ValueMember = "id";
adapter = new SqlDataAdapter("select id_w from wagon where id='" + comboBox1.SelectedValue + "'", cn);
adapter.Fill(ds, "wagon");
// adapter1.SelectCommand.Parameters.Clear();
comboBox2.DataSource = ds.Tables["wagon"];
comboBox2.DisplayMember = "id_w";
comboBox2.ValueMember = "id_w";