adding time from 2 cells in 3rd cell=#VALUE error

Hi all.
I'm trying to add (Formate) m/d h:mm, with =TODAY() in R26, with
(Formate) d h:mm in S26......

Formula '=R26+S26' in cell U26

all I get is #VALUE

Purpose: after entering the d h:mm value to S26, I need U26 to give me the m/d h:mm value, which is the format of the cell.
It's to give me the day and time that I need to attend to something that is expiring and needs to be renewed/reactivated.

I've tried 'S26=(NOW()+S26); S26=NOW()+S26; S26=NOW()+(S26)

anyone?