Try this code, it is similar to the last post:

VB Code:
  1. Option Explicit
  2.  
  3. Private Sub Form_Load()
  4.   Dim s As Date, m As Integer, x As Date, mm As String
  5.   s = CDate("2/1/2004")
  6.   mm = Format(s, "MMMM, yyyy")
  7.   s = DateSerial(Year(s), Month(s) + 1, 1)
  8.   x = DateAdd("d", -1, s)
  9.   MsgBox Day(x) & " days in " & mm
  10. End Sub