If/else statement on Test-WSMan

I'm trying to create a Powershell GUI function to show a Connected/Not connected status via a color bar, computername inserted via a TextBox input.

I'm using Test-WSMan function to have my output.

I'm a bit confused with my else/if statement.

It should pop-up a window if no computer inserted, if no test-WSMan is possible it throw a red error if connects it should have a green lights.

Even with an unknown computer i allways have green light and my code don't stop running.

Here's my code

function checkinfo {

$Server=$textboxComputername.text;

if (-not $textboxComputername.Text)
            {
                [System.Windows.Forms.MessageBox]::Show('No computer 
                specified', 'Error')
                Throw 'No Computer specified'
            }
elseif 

            (Test-WSMan  $Server ) {
            $label_PingStatus.Text = "OK";
            $label_PingStatus.ForeColor = "green"
            Write-Status -Message "Connected to $Server"
            $picturebox1.BackColor = "Green"
else 

            If (-not (Test-WSMan $Server))
            {
                $picturebox1.BackColor = "Red"
                Write-Status -Message "Not Connected to $Server"

                [System.Windows.Forms.MessageBox]::Show('No such computer or computer is offline', 'Error')
                Throw 'No such computer or computer is offline'

    }

Thanks for your guidance