Model stops working sometimes. CFrame nil SetPrimaryPartCFrame

Help and Feedback Scripting Support
#1 

if Torso.Parent:WaitForChild("Humanoid").MoveDirection.X == 0 then
            self:GetWalking()
           
            Model:SetPrimaryPartCFrame(Model.PrimaryPart.CFrame:Lerp(Torso.CFrame * CFrame.new(4,-3,0) * CFrame.fromOrientation(0,70,0), Step * 5))
            WalkBool = false
        else

            self:GetWalking(true)
            Model:SetPrimaryPartCFrame(Model.PrimaryPart.CFrame:Lerp(Torso.CFrame * CFrame.new(4,-3,0),Step * 5))
            WalkBool = true
        end

When walking this line sometimes breaks and says CFrame is nil.

Model:SetPrimaryPartCFrame(Model.PrimaryPart.CFrame:Lerp(Torso.CFrame * CFrame.new(4,-3,0) * CFrame.fromOrientation(0,70,0), Step * 5))

I am using Humanoid to animate pet.

#2

Are you sure you have set the PrimaryPart before using SetPrimaryPartCFrame?

#3

Duh. then how was it working for a minute.