Binding expression to bind a property of a class within a list to gridview
<p>Suppose I have a class which is defined as below which is the exact scenario of my project that I am working on.  </p>

<pre><code>School school = new School();
public partial class School{
private List&lt;Students&gt; student= new List&lt;Students&gt;();
    public List&lt;Students&gt; Students
    {
        get { return student; }
        set { invoice = student; }
    }
}  
 public partial class Students{
private List&lt;Marks&gt; mark= new List&lt;Marks&gt;();
    public List&lt;Marks&gt; Mark
    {
        get { return mark; }
        set { mark= value; }
    }
 }

public partial class Marks{
public string m1;
public string m2;
public string m3;
private StudentDetails studetails= new StudentDetails ();
    public StudentDetails StudentDetails 
    {
        get { return studetails; }
        set { studetails= value; }

    }     
    /// &lt;remarks/&gt;
    private TeacherDetails details= new TeacherDetails ();
    public TeacherDetails TeacherDetails 
    {
        get { return details; }
        set { details= value; }
    }   
    public decimal totalmarks;   
    }  
</code></pre>

<p>In this method I am adding items to the list and displaying them in the gridview  </p>

<pre><code>   public void Addtogrid()
    {
       school.Students[0].Marks.Add(new Students{m1= m1.Text, m2= m2.Text, m3= m3.Text });

        for (int i = 0; i &lt; school.Students[0].Marks.Count; i++)
        {
            school.Students[0].Marks[i].StudentDetails.Name= name.Text;
            school.Students[0].Marks[i].StudentDetails.Age= Convert.ToInt32(age.Text);
            school.Students[0].Marks[i].TeacherDetails.Name = tname.Text 
            school.Students[0].Marks[i].TeacherDetails.Age= tage.Text 

            school.Students[0].Marks[i].TotalMarks= (school.Students[0].Marks[i].StudentDetails.Age) * (school.Students[0].Marks[i].TeacherDetails.Age);
            GridView1.DataSource = school.Students[0].Marks;
            GridView1.DataBind();
            Session["BillXML"] = invoicetransmit;
        }
    }

 public void lblm1_OnDataBinding(object sender, System.EventArgs e)
    {
        Label lbl = (Label)sender;
        lbl.Text = Eval("m1").ToString();
    }
 public void lbltotalmarks_OnDataBinding(object sender, System.EventArgs e)
    {
        Label lbl = (Label)sender;
        lbl.Text = Eval("totalmarks").ToString();---property does not exist
    }
</code></pre>

<p>please let me know what is the binding expression for total marks to gridview. I am new to c#,lists , gridview ..</p>
