Converting Date Function For Both UK & USA

This function gets the last working day (Mon-Fri Are Deamed Working Days For Invoicing purposes) of a month adds it to a table then gets the next until it has done the Number indecated In "txtMonths", It works with a UK Date Format but not with a USA Date Format.

Is there A Better way of doing this or does anybody have an idear as to how I could correct it for UK and US Date Formats

Y = Year(Me![txtStartDate]) 'Get Added Year
M = Month(Me![txtStartDate]) 'Get Added month To Keep Track Of year Change
D = Weekday(Me![txtStartDate], vbMonday) 'Get Day of week and set to monday
On Error Resume Next
For C = 1 To Me![txtMonths]
DDt = CDate(1 & "/" & M & "/" & Y) 'Set to first of the month
Ld = LastOfMonth(DDt)
Nd = CDate(Ld & "/" & M & "/" & Y)
'StrSch = Ld & "/" & M & "/" & Y
CWd = Weekday(CDate(Ld & "/" & M & "/" & Y), vbMonday)
'Now If the date falls on a sat or sunday move the day back to friday
If CWd > 5 Then
If CWd = 6 Then D = 1
If CWd = 7 Then D = 2
Nd = CDate(Ld & "/" & M & "/" & Y) - D
End If
AddSchedule Nd
'Debug.Print C & " | " & StrSch & " | " & CWd & " | " & Nd & " | " & D
M = M + 1
If M > 12 Then
M = 1 'Only 12 Months in a year
Y = Y + 1 'Gotta be a new year Happy New Year
End If
Next C

Edit: Function used to get the last day of a given month

Function LastOfMonth(InputDate As Date) As Integer
' Return a date that is the last day of the month of the date passed
Dim D As Integer, M As Integer, Y As Integer

If IsNull(InputDate) Then
LastOfMonth = Null
Else
D = Day(InputDate)
M = Month(InputDate)
Y = Year(InputDate)
'find the first day of next month, then back up one day
LastOfMonth = Day(DateAdd("m", 1, DateSerial(Y, M, 1)) - 1)
End If
End Function