Not Getting Username/Player from text-box what do I do?

I have a situation where if I type a players username in the text-box the script is supposed to grab the player name I typed and go to Players and find the player and copy the tool in this case a coke into their backpack but I keep getting an error message on line 6.

Error Message From Console: Enter username is not a valid member of Players.

The text-box says Enter username but it shouldn't say error Enter username isn't a player when I changed the text to the players user already.

local a = game.ServerStorage.Items.Drinks -- Item Location

script.Parent.coke.MouseButton1Click:connect(function()
	if script.Parent.coke.Text == "Coke" then
		local new = a.Coke:Clone() -- Cloning Item
	new.Parent = game.Players[script.Parent.Username.Text].Backpack
	script.Parent.coke.Text = "Gave item!"
	wait(1)
	script.Parent.coke.Text = "Coke"
	end
end)

First of all :connect() is deprecated use :Connect() secondly input belongs on the client (localscript) and it doesnt work because when u make the changes to the textbox ur doing that as the client so the server doesnt have to changes, you ll have to use a localscript and a script and a remote event bewteen those

see remote events