First of All you need to create a Item Templet of DataList in which data will be displayed, then try this...
If reader.Read() Then
DataList1.DataSource = dictionary1.Tables("postcomment")
Me.DataBind()
Else
DataList1.Visible = False
nocomment.Text = "No Comments Posted"
End If
Inseted of Me.DataBind() please try to call a bind method of
DataList1.DataBind()