Drawing on HUD in VESSEL3 class causes CTD

[BrianJ]

Using latest Orbiter beta version 150307.

Writing text or drawing lines on the HUD in any of my VESSEL3 class add-ons causes a CTD when HUD is displayed(cockpit view).

Still works fine for my VESSEL2 class add-ons.

This works OK(VESSEL2 class)

///// class interface
class f9h_stg2: public VESSEL2 
{
public:
    f9h_stg2 (OBJHANDLE hVessel, int flightmodel);
    ~f9h_stg2 ();
    void clbkDrawHUD (int mode, const HUDPAINTSPEC *hps, HDC hDC);
}

///// HUD 
void f9h_stg2::clbkDrawHUD (int mode, const HUDPAINTSPEC *hps, HDC hDC)
{

    char kbuf[256];
    sprintf(kbuf,"TEST TEST TEST");
    TextOut(hDC,(100),(100),kbuf,strlen(kbuf));
  
}

This causes CTD (VESSEL3 class)

///// class interface
class f9h_stg2: public VESSEL3 
{
public:
    f9h_stg2 (OBJHANDLE hVessel, int flightmodel);
    ~f9h_stg2 ();
    bool clbkDrawHUD (int mode, const HUDPAINTSPEC *hps, oapi::Sketchpad *skp);
}

///// HUD
bool f9h_stg2::clbkDrawHUD (int mode, const HUDPAINTSPEC *hps, oapi::Sketchpad *skp)
{
    // draw the default HUD
    VESSEL3::clbkDrawHUD (mode, hps, skp);

    char kbuf[256];
    sprintf(kbuf,"TEST TEST TEST");
    skp->Text((100),(100),kbuf,strlen(kbuf));

    return true;
}

I see the default shuttle Atlantis manages to draw on the HUD with no problems, and from the sample sdk code it looks like Atlantis is VESSEL3 class - so, am I missing something from my code?

Cheers,
BrianJ

EDIT------------------------------
Compiling with the OrbiterBeta r.13 SDK libraries solves the problem.