i have exception Conversion from string "System.Web.UI.WebControls.TextBo" to type 'Integer' is not valid.
on these line
Dim no_single_room As Int32 = CType(DirectCast(dataItem.FindControl("txt_single"), TextBox).ToString(), Int32)
Dim no_double_room As Int32 = CType(DirectCast(dataItem.FindControl("txt_double"), TextBox).ToString(), Int32)