How to weld a shockwave when a user presses a button?

Sorry I am asking this again I am just super confused I keep getting "HumanoidRootPart is not a valid member of model"

local uis = game:GetService('UserInputService')
local player = game.Players.LocalPlayer
local shockwave = game.Workspace.Shockwave
local connect = player.Character.HumanoidRootPart

shockwave.Transparency = 1

local weld = Instance.new('Weld')
weld.Part0 = connect
weld.Part1 = shockwave
weld.Parent = connect

uis.InputBegan:Connect(function(input, proccessedEvent)
	if input.UserInputType == Enum.UserInputType.Keyboard then
		if input.KeyCode == Enum.KeyCode.C then
			shockwave.Transparency = 0
		end
		shockwave.Transparency = 1
	end
end)

I changed the code a bit and it seemed to work

local inputService = game:GetService("UserInputService")
local player = game.Players.LocalPlayer
local shockwave = workspace:WaitForChild("Shockwave")
local connect = workspace:FindFirstChild(player.Name)

shockwave.Transparency = 1

local weld = Instance.new("Weld")
weld.Part0 = connect
weld.Part1 = shockwave
weld.Parent = connect

inputService.InputBegan:Connect(function(input, gameProcessed)
	if input.UserInputType == Enum.UserInputType.Keyboard then
		if input.KeyCode == Enum.KeyCode.C then
			shockwave.Transparency = 0
		end
	end
end)

For some reason it doesn't create the weld, but it doesn't give any errors so I don't know what's happening there.

If you want to make the shockwave disappear when the key is released you can use the InputEnded event.