The macro below was applied to the dates given to obtain numbers of
days. Instead, it keep producing the RESULT in serial-like faction.
What do I do to achieve the expected result shown below?

dim tx as Date
tx = Format(#1/1/2008#, "dd/mm/yyyy")

Range("F" & z).FormulaR1C1 = "=RC[-1] - " & (tx)


DATE
30/01/2008
31/1/2008
31/1/2007

RESULT
39477
39478
39478

EXPECTED RESULT(NO OF DAYS)
29
30
30
30