title: How to add 1 month to selected DateTimePicker
body: <p>I'm having an issue with DateTimePicker. </p>
  
  <p>What I am currently trying to do is based off of what text is in lblPrevSem(Previous Semester), which is getting its selection from a drop down on a previous screen, i want to add a certain amount of time to the DateTimePicker. </p>
  
  <pre><code>Public Property CustomFormat As String
  Dim SemesterMonths As Integer
  Dim SemesterDays As Integer
  
  
  Private Sub DeptCreatePrevSch_Load(sender As Object, e As EventArgs) Handles MyBase.Load
      Dim SemesterYear() As String = DeptPrevSch.CboSem.Text.Split(",")
  
  
      lblPrevSem.Text = SemesterYear(0)
      cboYear.Text = Date.Now.Year
      For i As Integer = 0 To 5
          cboYear.Items.Add(Date.Now.Year + i)
          cboYear.SelectedIndex = 0
      Next
  
      If InStr(lblPrevSem.Text, "Fall") Then
          SemesterMonths = 1
      ElseIf InStr(lblPrevSem.Text, "Spring") Then
          SemesterMonths = 1
      ElseIf InStr(lblPrevSem.Text, "Summer") Then
          SemesterDays = 14
      End If
  
      Call dtpStart_ValueChanged(sender, e)
  End Sub
  
  Private Sub dtpStart_ValueChanged(sender As Object, e As EventArgs) Handles dtpStart.ValueChanged
  
      Dim StartDate As Date
      Dim StartStringDate As String
      Dim EndDate As Date
      Dim EndStringDate As String
  
  
      dtpStart.Format = DateTimePickerFormat.Custom
      dtpStart.CustomFormat = "MMMM dd, yyyy  dddd"
  
      StartDate = dtpStart.Value.ToString
      StartStringDate = StartDate.ToString("MMMM dd, yyyy  dddd")
      lblRegStartDate.Text = StartStringDate
  
      EndDate = dtpStart.Value.AddMonths(SemesterMonths)
      EndDate = dtpStart.Value.AddDays(SemesterDays)
      EndStringDate = EndDate.ToString("MMMM dd, yyyy  dddd")
      lblRegEndDate.Text = EndStringDate
  
  End Sub
  </code></pre>
  
  <p>I can get it to add in days just fine but when ever i try and add in 1 month, it doesn't seem to work at all. </p>
  
  <p>I've tried multiple different ways to add in a 1 month but nothing so far has worked. The closet ive been was adding in 30 days but then that doesn't account for months that have 31 days.</p>
  
  <p><strong>Reg Start Date</strong> is what ever the DateTimePicker is and <strong>Reg End Date</strong> should be the added days based off of what lblPrevSem is </p>
  
  <p>Both Reg Start/End Date are displayed as labels</p>
  
  <p>(i.e. Fall = 1 Month, Spring = 1 Month, Summer = 2 Weeks)</p>