solve the problem

Question

I have three tables course,faculty,student.I have implemented one to many relation between tables using primary key constraint & foreign key constraint.my design consists of one dropdownlist & two datagridviews.I bind the common column of course table to dropdownlist.when i select the combobox item it will display corresponding faculty table records in one gridview & student table records in another gridview.these are in form load only.I get the result in C# Windows forms.but i am not getting same result in ASP.net. it is binding
courseid to dropdownlist & faculty table to  gridview1,student table to gridview2.problem is when I select the dropdownlist item the corresponding table data does not displayed in corresponding gridviews.but I get the result in C# winforms with same bellow code(dropdownlist==combobox).if any body knows please give solution clearly.
I set the dropdownlist property autopostback is true  .
private void Form1_Load(object sender, EventArgs e)
{
string cs = "uid=sa;pwd=nanda;database=satyadatabase";
SqlConnection conn = new SqlConnection(cs);
// conn.Open();
SqlCommand cmd1 = new SqlCommand("select * from course", conn);
SqlCommand cmd2 = new SqlCommand("select * from faculty", conn);
SqlCommand cmd3 = new SqlCommand("select * from student", conn);
SqlDataAdapter da1 = new SqlDataAdapter(cmd1);
SqlDataAdapter da2 = new SqlDataAdapter(cmd2);
SqlDataAdapter da3 = new SqlDataAdapter(cmd3);
DataSet ds = new DataSet();
da1.Fill(ds, "coursenew");
da2.Fill(ds, "facultynew");
da3.Fill(ds, "studentnew");
ds.Relations.Add("coursefac", ds.Tables["coursenew"].Columns["courseid"], ds.Tables["facultynew"].Columns["courseid"]);
ds.Relations.Add("coursest", ds.Tables["coursenew"].Columns["courseid"], ds.Tables["studentnew"].Columns["courseid"]);
Dropdownlist1.DataSource = ds.Tables["coursenew"];
Dropdownlist1.DataValueField = "courseid";
gridfaculty.DataSource = ds.Tables["coursenew"];
gridfaculty.DataMember = "coursefac";
gridstudent.DataSource = ds.Tables["coursenew"];
gridstudent.DataMember = "coursest";
}

Mike Gold · Answer

probably need to see how your dropdownlist is set up on the asp.net page.  Also check to see if the data is showing up in your data set in the asp.net code.