My BodyVelocity script only works sometimes, and the rest of the time it dosent work, any ideas?

local Force = script.Parent.Parent:FindFirstChildWhichIsA('BodyVelocity',true)
local Mass = 0

for i,v in pairs(script.Parent.Parent:GetChildren()) do
	if v:IsA("BasePart") then
		Mass = Mass + v:GetMass()
	end
end

 script.Parent.ClickDetector.MouseClick:Connect(function()
	Force.MaxForce = Vector3.new(0,Mass*(workspace.Gravity*1.2),0)
	Force.Velocity = Vector3.new(0,50,0)

Got any ideas?
	

Nvm guys, I just anchored the rocket to the ground. Silly me!