Thanks Scott,
Understood what you explained and thank you, but regardless of calculation, the issue is in model builder when you map the Elevation with the excel elevation; it does taken and shown in the properties and displayed while it is not in the flextable.
what about other question which was " One more question; why in the properties "Set Invert to Start/Stop" is gray? it means not editable, I guess this should be editable to change True to false??"
Thanks.........Mohamad