How do you get a Headshot image of a player?

Hello,

So when I am running this function. The script is supposed to get a random player's headshot. Should be quite simple, although this is my first timing using player-images, and it doesn't seem to work! I'm not sure what I am doing wrong.

This is my script, everything works fine when running the function, but the image won't load, Why does the request fail?

function PlayerTextAni()
    local p = Players:GetPlayers()
    local selected_value = math.random(1,#p)
    local UserId = p[selected_value].Name
    local GuiType = PlayerText
    local GuiText = Text
    GuiType.Frame.Player.Image = "https://www.roblox.com/headshot-thumbnail/image?username="..(UserId).."48103520&width=420&height=420&format=png"
    GuiType.Frame.Visible = true
    for i = 1, #GuiText do
        GuiType.Frame.Frame.Text.Text = string.sub(GuiText, 1, i)
        TextSound:Play()
        wait(0.05)
    end
    wait(2)
    GuiType.Frame.Frame.Text.Text = ""
    GuiType.Frame.Visible = false
end

Thanks for helping, Simon.