Android Question adding an entry to Calendar

Sub btnSave_Click
    Dim chkDay As Int
    DateTime.DateFormat = "dd/MM/yyyy"
    DateTime.TimeFormat =  "HH:mm"
    Dim ChkDate As String = DateTime.Date(Main.DateRet)
    If chkAllDay.Checked = True Then
        Dim    tfrom As Long =  Main.DateRet
        Dim tTo As Long = Main.DateRet
        chkDay=1
    Else
        If btnTimeFrom.xLBL.Text = "" Then 'needs better error checking
            Msgbox("No time entered or All day not checked", "Time(s) or All day required")
            Return
        End If
        Dim    tfrom As Long =  DateTime.datetimeParse(ChkDate,btnTimeFrom.xLBL.Text)
        Dim tTo As Long = DateTime.datetimeParse(ChkDate,btnTimeTo.xLBL.Text)
        chkDay=0
    End If
    Log("chkDate " & ChkDate  & " tTo " & tTo & " tfrom " & tfrom)
    Dim econValues As List
    econValues.Initialize
    econValues.Add(Main.wmCalendar1.econ.ALL_DAY)
    econValues.Add(Main.wmCalendar1.econ.DESCRIPTION)
    econValues.Add(Main.wmCalendar1.econ.DTEND)
    econValues.Add(Main.wmCalendar1.econ.DTSTART)
    econValues.Add(Main.wmCalendar1.econ.TITLE)
    econValues.Add(Main.wmCalendar1.econ.ORGANIZER)
    econValues.Add(Main.wmCalendar1.econ.LOCATION)
    econValues.Add(Main.wmCalendar1.econ.EVENT_END_TIMEZONE)
    econValues.Add(Main.wmCalendar1.econ.EVENT_TIMEZONE)
        Dim theEvent As EventInfo
        theEvent.Initialize
        theEvent.allDay = chkDay
        theEvent.description = txtDescription.Text
        theEvent.visible = 1
        theEvent.dateTimeEnd = tTo
        theEvent.dateTimeStart = tfrom
        theEvent.title = txtTitle.Text
        theEvent.organizer = txtOrganiser.Text
        theEvent.location = txtLocation.Text
        theEvent.timeZone = "UTC"
        theEvent.endTimeZone = "UTC"
        Log("the event " & theEvent)
    Dim newEventID As Int = Main.wmCalendar1.AddEvent(Main.ScalendarID, theEvent, econValues)
    If newEventID < 0 Then
        Msgbox("The Entry could not be added", "DITL Calendar")
    Else
        
        Msgbox("The Entry has been added", "DITL Calendar")
    End If
    StartActivity(Main)
End Sub