Date -Time not populating correctly

[snb]

or as UDF
"=F_snb(A1,True)"

Function F_snb(D, DayShift)
   F_snb = Abs(Hour(D) = 23 Or D < 0.25)
   If DayShift Then F_snb = Abs(D >= 0.25 And Hour(D) < 23)
End Function