Making 2D friction in a GUI and the player does not slide on surface when not moving, help?

For some reason the deceleration is not working. so when player stops pressing the arrow key he doesn't slide :(

local PlayerVelocity = script.Parent:WaitForChild("PlayerVelocity")
local PlayerMovementValue = script.Parent:WaitForChild("PlayerMovementValue")
local uis = game:GetService("UserInputService")

--Whenever player is moving, MovementValue is equal to 1.
--Whenever player is _not_ moving, MovementValue is equal to 0.

uis.InputBegan:connect(function(input,gp)
   if input.KeyCode == Enum.KeyCode.Left  then
--[[Accelerating:]] 
while PlayerMovementValue.Value == 1 do
    wait()
    if (PlayerVelocity.Value < 0) then

        PlayerVelocity.Value = (PlayerVelocity.Value + 0.5)*PlayerMovementValue.Value

    elseif (PlayerVelocity.Value < 3) then

        PlayerVelocity.Value = (PlayerVelocity.Value + 0.046875)*PlayerMovementValue.Value
else
--[Decelerating]]
 PlayerVelocity.Value = PlayerVelocity.Value -math.min(math.abs(PlayerVelocity.Value),0.046875)
*math.sign(PlayerVelocity.Value)
end
end 
end
end)