Common Error: Script works in studio but doesn't run in actual game?

I coded a script that will kick a ball to a certain position on mouse that works in studio, however does not work in the actual game (the script is located in the starterGui). How do you fix this?

--[[HYBRIC KEY CONTROLS:
    CLICK: SHOOT, A COUNTER VALUE WILL DETERMINE THE POWER/VELOCITY OF BALL
]]
Master = game.Players.LocalPlayer
mouse = Master:GetMouse()
local minShotValue = 10
local maxValue = 20
local isHold = false
local TelePos = Master.Character.Humanoid.TargetPoint
local targetPos = mouse.Hit.p
local DEBOUNCE = false
function l()--indicate you have began trick shot
    if (game.Players[Master.Name] ~= nil) then
        game.Players[Master.Name].PlayerGui.isDoingTrick.Value = true
    end
end
function l2()--indicate you have began trick shot
    if (game.Players[Master.Name] ~= nil) then
        game.Players[Master.Name].PlayerGui.isDoingTrick.Value = false
    end
end
function update()
    if (game.Players[Master.Name] ~= nil) then
    game.Players[Master.Name].PlayerGui.isDoingTrick.shooting.customPower.Value = minShotValue
    end
end

mouse.Button1Up:connect(function(mouse_up) --Hold Mouse
if (not DEBOUNCE) then
    DEBOUNCE=true
l()
print("MOUSE DOWN")
minShotValue = 0;
game.Players[Master.Name].PlayerGui.isDoingTrick.Value = false
game.Players[Master.Name].PlayerGui.isDoingTrick.shooting.Value = false
game.Players[Master.Name].PlayerGui.shootingGui.Frame.Visible = false
game.Players[Master.Name].PlayerGui.shootingGui.Frame.sizer.Size = UDim2.new(0,0,1,0);
DEBOUNCE = false;
--i have to script a reset value when the ball gets hit
end
end)


mouse.Button1Down:connect(function(mouse_down) --Hold Mouse
if (not DEBOUNCE) then
    DEBOUNCE=true
l()
print("MOUSE UP")
minShotValue = 1
local hitLoc = game.Lighting.shotT:Clone()
hitLoc.Parent = game.Players[Master.Name].PlayerGui
game.Players[Master.Name].PlayerGui.isDoingTrick.shooting.Value = true;
game.Players[Master.Name].PlayerGui.shootingGui.Frame.Visible = true;
game.Players[Master.Name].PlayerGui.beforeKick:Clone().Parent = game.Players[Master.Name].Character
--game.Players[Master.Name].Character.beforeKick:Play()
while minShotValue<=maxValue and workspace.soccerBall.justTouched.Value == false do
game.Players[Master.Name].PlayerGui.isDoingTrick.shooting.hitPos.Value = hitLoc.Position
hitLoc.Position = mouse.hit.p
game.Players[Master.Name].PlayerGui.shootingGui.Frame.sizer.Size = UDim2.new(minShotValue/maxValue,0,1,0);
    wait(0.1)
    minShotValue = minShotValue + 1
    update()
    --print(""..minShotValue)
end
wait(1)
game.Players[Master.Name].PlayerGui.isDoingTrick.Value = false
game.Players[Master.Name].PlayerGui.isDoingTrick.shooting.Value = false
wait(2)
game.Players[Master.Name].PlayerGui.shootingGui.Frame.Visible = false
game.Players[Master.Name].PlayerGui.shootingGui.Frame.sizer.Size = UDim2.new(0,0,1,0);
hitLoc:remove()
wait()
DEBOUNCE=false
end
--i have to script a reset value when the ball gets hit
end)

mouse.KeyDown:connect(function(key) 
key:lower() 
local TelePos = Master.Character.Humanoid.TargetPoint
local targetPos = mouse.Hit.p
            if key == "q" then

    end     
end)

Output:

Players.Hybric.PlayerGui.skillShots:10: attempt to index field 'Character' a nil value

im assuming i need to do waitforchild method