Base Form wouldn't save a result when return by a function

So here is what is happening…

My form has a field named fldTime1, user inputs a time here and hit ENTER (after change) a function pick up this fldTime1 value and add an hour to it and display it back to field name fldTime2. for example fldTime1 input is “10:00 am” goes thru function, function return its result at fldTime2 “11:00 am”…up to this point all good and working as I intended. Problem is once the value comes back to fldTime2 (updated info) if I hit the SAVE (button will be bold) …nothing saved into the table. Only way I can save it If I go to fldTime2 Field and edit it then it will save its value by hitting SAVE button.

I am not sure what I am missing…it is very annoying PLEASE HELP