I can't figure out what's wrong with this script (?)

What's the problem with this script? I am working on a Pokemon game an I need to make collectible items. This is the script for the rock item that is supposed to add 1 additional rock when clicked. The middle is not really important, I think. It works fine if I replace "function onClicked(part)" with "function onTouched(part)" and "script.Parent.ClickDetector.MouseClick:connect(onClicked)" with "script.Parent.Touched:connect(onTouched)", but that's not what I want to do with the script. I can provide more information if needed. Yes, I put ClickDetector inside the part. Thanks.

local amnt = 1

function onClicked(part)
 local h = part.Parent:findFirstChild("Humanoid")
 if (h~=nil) then
  local thisplr = game.Players:findFirstChild(h.Parent.Name)
  if (thisplr~=nil) then
   local stats = thisplr:findFirstChild("stats")
   if (stats~=nil) then
    local score = stats:findFirstChild("Rock")
    if (score~=nil) then
score.Value = score.Value + amnt
         end
   end
     end
script.Parent:remove()
 end
end

script.Parent.ClickDetector.MouseClick:connect(onClicked)

The MouseClick event has a parameter that shows which player clicked the button. With that being said, you can get rid of the first few lines and edit the stats variable line to point to the player.

local amnt = 1

function onClicked(plr) --Changing the variable name so we know it's the player.
	local stats = plr:findFirstChild("stats")
	if stats then --More efficient way of finding if stats is available.
		local score = stats:findFirstChild("Rock")
		if score then
			score.Value = score.Value + amnt
		end
  	 end
	script.Parent:remove()
end

script.Parent.ClickDetector.MouseClick:connect(onClicked)

Also, you can use a debounce variable to make sure the player gets one rock and one rock only.

local amnt = 1
local db = false

function onClicked(plr) --Changing the variable name so we know it's the player.
	if db then return end --If the db variable is true, stop the function.
	db = true --Set the variable to true so other instances of the function don't fire.
	local stats = plr:findFirstChild("stats")
	if stats then --More efficient way of finding if stats is available.
		local score = stats:findFirstChild("Rock")
		if score then
			score.Value = score.Value + amnt
		end
  	 end
	script.Parent:remove()
end --Usually, you'd set db to false to allow other instances of the function to run, but since the script is being deleted (as you're removing it's parent), there's not need to do this.

script.Parent.ClickDetector.MouseClick:connect(onClicked)

If this helped, please upvote and accept my answer. :)

Further reading:

MouseClick event

Debounce