Public Class Form1
    Private Sub lstEmployees_SelectedValueChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles lstEmployees.SelectedValueChanged
        If lstEmployees.SelectedIndex >= 0 Then
            btn1.Enabled = True
        End If
    End Sub

    Private Sub lstExcursion_SelectedValueChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles lstExcursion.SelectedValueChanged
        If lstExcursion.SelectedIndex >= 0 Then
            btn2.Enabled = True
        End If
    End Sub

    Private Sub btn2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn2.Click
        lstExcursion.Items.RemoveAt(lstExcursion.SelectedIndex)
        lblol.Text = lblol.Text - 1
        btn2.Enabled = False
    End Sub

    Private Sub btn1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn1.Click
        lstExcursion.Items.Add(lstEmployees.Text)
        lblol.Text = lblol.Text + 1
        btn1.Enabled = False
    End Sub
End Class