Dropdown selection in powershell script - powershell

Question

I created a script for ping the some IP Address. So I am trying to drop down selection. But in the dropdown selection text file input data is showing. But I cannot get the selected value in drop down selection.
Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing
$Form1 = New-Object system.Windows.Forms.Form
$Form1.ClientSize = ‘600,450’
$Form1.text = “PowerShell GUI Example”
$Form1.BackColor = “#ffffff”
$List = New-Object system.Windows.Forms.ComboBox
$List.text = “”
$List.width = 170
$List.autosize = $true
# Add the items in the dropdown list
[array]$result = (Get-Content E:\IP.txt)
$result | ForEach-Object {[void] $List.Items.Add($_)}
# Select the default value
$List.SelectedIndex = 0
$List.location = New-Object System.Drawing.Point(70,100)
$List.Font = ‘Microsoft Sans Serif,10’
$List.add_SelectedIndexChanged({
$selected = $List.SelectedItem
write-host $selected
#$Description.text = “Selected index: $selected”
})
$Form1.Controls.Add($List)
# Add a Button which can be used to generate an action from our textboxes
$Button = New-Object System.Windows.Forms.Button
$Button.Location = New-Object System.Drawing.Size(10,10)
$Button.Size = New-Object System.Drawing.Size(100,40)
$Button.Text = "PING"
# Declare the action to occur when button clicked
$Button.Add_Click( { PING } )
# Initialize the button inside the Form
$Form1.Controls.Add($Button)
# Create a Function to make use of textboxes
function PING {
Ping.exe -t $selected | ForEach {"{0} - {1}" -f (Get-Date),$_} | Tee-Object E:\ping.txt -Append | Out-GridView -Title 'PING'
}
# Display the form
[void]$Form1.ShowDialog()