Date calculation Fails

Sub Globals
   'These global variables will be redeclared each time the activity is created.
   'These variables can only be accessed from this module.
   Dim Startdatum,Datum_count As Long
   Dim label1, label2 As Label
End Sub

Sub Activity_Create(FirstTime As Boolean)
   label1.Initialize("")
   label2.Initialize("")
   activity.AddView(label1,0dip,0dip,300dip,120dip)
   activity.AddView(label2,0dip,100dip,300dip,220dip)
   
   DateTime.DateFormat = "dd.MM.yyyy"
   
   startdatum = DateTime.DateParse("30.10.2011")
   
   Datum_count = Startdatum
   datum_count = datum_count + DateTime.TicksPerDay
   
   label1.Text = "Startdatum:" & DateTime.Date(startdatum) & CRLF &"Startdatum + 1 Tag: " & DateTime.Date(datum_count)


   startdatum = DateTime.DateParse("31.10.2011")
   
   Datum_count = Startdatum
   datum_count = datum_count + DateTime.TicksPerDay
   
   label2.Text = "Startdatum:" & DateTime.Date(startdatum) & CRLF &"Startdatum + 1 Tag: " & DateTime.Date(datum_count)



End Sub

Sub Globals
   Dim Startdatum,Datum_count As Long
   Dim label1, label2 As Label
End Sub

Sub Activity_Create(FirstTime As Boolean)
   DateTime.DateFormat = "dd.MM.yyyy"
   startdatum = DateTime.DateParse("30.10.2011")
   datum_count = Startdatum
   datum_count = datum_count + DateTime.TicksPerDay
   Log(DateTime.Date(datum_count) & " " & DateTime.Time(Datum_count))
   startdatum = DateTime.DateParse("31.10.2011")
   Datum_count = Startdatum
   datum_count = datum_count + DateTime.TicksPerDay
   Log(DateTime.Date(datum_count) & " " &  DateTime.Time(Datum_count))
End Sub

** Activity (main) Create, isFirst = true **
31.10.2011 00:00:00
01.11.2011 00:00:00
** Activity (main) Resume **

** Activity (main) Create, isFirst = true **
30.10.2011 23:00:00
01.11.2011 00:00:00
** Activity (main) Resume **

DateTime.SetTimezome(0)

startdatum = DateTime.Add(datedialogticks, 0, 0, -280)

datum_count = datum_count + DateTime.TicksPerDay

datum_count = DateTime.Add(datum_count, 0, 0, 1)