Selecting Items as variables

I am, for the first time, trying to create a popup selectable item list in powershell. Can someone help me understand why this code is not defining the $Printer1 variable?

#Extract Printer list from Active Directory
$Printerlike = $AutoLogonAccountName -replace ".{5}$" #drop the last 5 characters
$PrinterList = (Get-ADGroup -Filter * | Where {$_.name -like "ptr.gs.$Printerlike*"}).name

#Prompt for Primary Printer Selection
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")
[void] [System.Reflection.Assembly]::LoadWithPartialName("System.Drawing")

$objForm = New-Object System.Windows.Forms.Form
$objForm.Text = "Select a Primary Printer"
$objForm.Size = New-Object System.Drawing.Size(300,200)
$objForm.StartPosition = "CenterScreen"

$objForm.KeyPreview = $True
$objForm.Add_KeyDown({if ($_.KeyCode -eq "Enter")
    {$Printer1=$objListBox.SelectedItem;$objForm.Close()}})
$objForm.Add_KeyDown({if ($_.KeyCode -eq "Escape")
    {$objForm.Close()}})

$OKButton = New-Object System.Windows.Forms.Button
$OKButton.Location = New-Object System.Drawing.Size(75,120)
$OKButton.Size = New-Object System.Drawing.Size(75,23)
$OKButton.Text = "OK"
$OKButton.Add_Click({$Printer1=$objListBox.SelectedItem;$objForm.Close()})
$objForm.Controls.Add($OKButton)

$CancelButton = New-Object System.Windows.Forms.Button
$CancelButton.Location = New-Object System.Drawing.Size(150,120)
$CancelButton.Size = New-Object System.Drawing.Size(75,23)
$CancelButton.Text = "Cancel"
$CancelButton.Add_Click({$objForm.Close()})
$objForm.Controls.Add($CancelButton)

$objLabel = New-Object System.Windows.Forms.Label
$objLabel.Location = New-Object System.Drawing.Size(10,20)
$objLabel.Size = New-Object System.Drawing.Size(280,20)
$objLabel.Text = "Please select a Default Printer:"
$objForm.Controls.Add($objLabel)

$objListBox = New-Object System.Windows.Forms.ListBox
$objListBox.Location = New-Object System.Drawing.Size(10,40)
$objListBox.Size = New-Object System.Drawing.Size(260,20)
$objListBox.Height = 80

$PrinterList | ForEach-Object {[void] $objListBox.Items.Add($_)}

#[void] $objListBox.Items.Add("atl-dc-001")
#[void] $objListBox.Items.Add("atl-dc-002")
#[void] $objListBox.Items.Add("atl-dc-003")
#[void] $objListBox.Items.Add("atl-dc-004")
#[void] $objListBox.Items.Add("atl-dc-005")
#[void] $objListBox.Items.Add("atl-dc-006")
#[void] $objListBox.Items.Add("atl-dc-007")

$objForm.Controls.Add($objListBox)

$objForm.Topmost = $True

$objForm.Add_Shown({$objForm.Activate()})
[void] $objForm.ShowDialog()