First, did you put it into TC Ti mode? alot of people put it in TC Ni mode by accident, and it just won't work that way.
Second, did you let the coils readjust to room temp after installing them in the RDA? This is crucial, as the mod won't read the TCR correctly, and kick you out of TC mode.
Third, are you sure there are no shorts? I know it's kinda hard to tell since it's TC wire and can't be dry-fired, but a short may kick you out of TC mode also.
And too lock the resistance (ONLY after letting the coils readjust to room temp) triple tap the fire button (this will give you the ability to scroll through the menu options) scroll down to the "Ohms/resistance" reading, then select it and the resistance will lock (indicated by the little padlock icon)