Thanks for everyone posting their theories on how to get and display the
number of days based on which month is selected, but I actually found a
solution to my problem.

Create a project and place two combos on the form then place the following
code into the project:

    Private Sub Combo1_Click ()
        Dim i As Integer
        Combo2.Clear
        For i = 1 to DateDiff("d", DateValue(Combo1.Text & "/1/" & _
                Format(Now(), "yyyy")), DateAdd("m", 1, Combo1.Text & _
                "/1/" & Format(Now(), "yyyy")))
            Combo2.Additem i
        Next i
    End Sub

    Private Sub Form1_Load ()
        Dim i As Integer
        For i = 0 to 11
            Combo1.Additem Format(DateAdd("m", i, DateValue("1/1/" & _
                Format(Now(), "yyyy"))), "mmmm")
        Next i
    End Sub

This code will even account for Leap Years. Just try it, it does work.
Change your system date to the year 2000, 2004 and so on and select February
from the first combo. Then display the value in the second combo.

Darren O'Leary