First check, your table has data.
You can bind gridview with dataset as, first declare a public dataset like
public dataset ds;
string s = Session["MenuItem"].ToString();
int TypeId = getTypeId(Session["MenuItem"].ToString());
Adapter = new SqlDataAdapter("SELECT Title,Date,Time,AgeId FROM Subjects WHERE CId = '"+TypeId+"'", con);
Adapter.Fill(ds, "Subjects")
GridView1.DataBind();;
<asp:GridView DataSource='<%#ds>' ID="GridView1" runat="server" AllowPaging="True" AutoGenerateColumns="False">
</asp:GridView>
as you can notice in source i have added DataSource property for gridview
Try this.