Adding bone with lua, set advance props, del it, switch laye

[Tha Narie]

When adding a bone with .lua, and setting soms advance properties listed below, deleting the bone, and switching layers, Moho crashes.
Only when deleting the bone.
Even after doing some other work before deleting.

List of properties that cause Moho to crash:
-- nb.fAngleControlParent = -1
-- nb.fPosControlParent = -1
-- nb.fScaleControlParent = -1

-- nb.fAngleControlScale = ob.fAngleControlScale
-- nb.fPosControlScale:Set(ob.fPosControlScale)
-- nb.fScaleControlScale = ob.fScaleControlScale

-- nb.fBoneDynamics = ob.fBoneDynamics
-- nb.fTorqueForce = ob.fTorqueForce
-- nb.fSpringForce = ob.fSpringForce
-- nb.fDampingForce = ob.fDampingForce

List of properties that work:
nb.fLength = ob.fLength
nb.fStrength = ob.fStrength
nb.fOffset:Set(ob.fOffset)
nb.fAnimScale:SetValue(moho.frame, ob.fScale)
nb.fAnimAngle:SetValue(moho.frame, ob.fAngle)
nb.fAnimPos:SetValue(moho.frame, ob.fPos)
nb.fConstraints = ob.fConstraints
nb.fMinConstraint = ob.fMinConstraint
nb.fMaxConstraint = ob.fMaxConstraint


Moho 5.3.1
Windows XP (notebook)
AMD Athlon(tm) 64 X2 Dual Core Processor 4400+
2 GB 400Mhz DDR-SDRAM
NVIDIA GeForce Go 7800 GTX 265MB