Problems with type fields

Ok, I seem to be having a weird problem here. I'm trying to encapsulate the IrrBMAX commands into helper functions to make it a little easier. Problem is that one of the fields keep changing to null for no apparent reason.

Strict
Import gg.irrBMAX

Type T_I3D
 Field device:T_irrIrrlichtDevice
 Field driver:T_irrIVideoDriver
 Field smgr:T_irrISceneManager
 Field guienv:T_irrIGUIEnvironment


 Method Graphics3D:Int(width:Int, height:Int, BPP:Int = 16, WindowMode:Int = False, ..
                         VSync:Int = False,Driver = EDT_OPENGL,Shadow:Int = False)

  device = T_irrIrrlichtDevice.create(Driver,T_irrDimension2d_s32.create(Width,Height), ..
                                   BPP,WindowMode,Shadow,VSync)
  If device = Null Then Return False
DebugLog("Graphics3D device "+(device<>Null))
  driver = device.getVideoDriver()
DebugLog("Graphics3D driver "+(driver<>Null))
  smgr = device.getSceneManager()
DebugLog("Graphics3D smgr "+(smgr<>Null))
  guienv = device.getGUIEnvironment()
DebugLog("Graphics3D guienv "+(guienv<>Null))
  Return True
 End Method

 Method SetCaption(cap:String)
  device.setWindowCaption(cap)
 End Method

 Method BeginScene(red:Int,green:Int,blue:Int,alpha:Int = 0)
  driver.beginScene(True,True,T_irrSColor.createFromVals(0,200,200,200))
 End Method

 Method EndScene()
  driver.endScene()
 End Method

 Method RenderAll()
  smgr.drawAll()
  guienv.drawAll()
 End Method

 Method Run:Int()
  Return Device.Run()
 End Method

 Method EndGraphics3D()
  device.drop()
 End Method

End Type

Local I3D:T_I3D = New T_I3D
I3D.Graphics3D(640,480,32)
DebugLog ("Main device "+(I3D.device <> Null))
DebugLog ("main driver "+(I3D.driver <> Null))
DebugLog ("Main smgr "+(I3D.smgr <> Null))
DebugLog ("Main guienv "+(I3D.guienv <> Null))

I3D.SetCaption("Test App")

While (I3D.Run())
 I3D.BeginScene(200,200,200)
 I3D.RenderAll()
 I3D.EndScene()
Wend

I3D.EndGraphics3D()

So why does driver become null after exiting the Graphics3D method, but device, smgr, and guienv do not?
I even tried using Global fields and Functions and calling them directly, but same problem there as well.