watchdog watchdog0: watchdog did not stop!

I'm using PTXdist 2012.12 with a Mini2440. I initialize and kick the
watchdog from my Qt application. It used to work fine with kernel 2.6.38
but now with kernel 3.7 I get the following error:

watchdog watchdog0: watchdog did not stop!

This is the code I use to initialize and kick the dog:

//******************************************************************************
**
// Watchdog constructor
//******************************************************************************
**
cWatchdog::cWatchdog(cSystem *fSystem)
{
  WatchDogTimeout = 30;

  System = fSystem;

  QObject::connect(this, SIGNAL(signalAddStatusText(QString)),
System->GUI->StatusDialog, SLOT(AddStatusText(QString)));

  emit signalAddStatusText("Watchdog initialization");

  // Try and get a handle to the watchdog
    WatchdogHandle = open("/dev/watchdog", O_WRONLY);
  // If the handle is not valid
  if (WatchdogHandle < 0)
  {
    perror("Could not get a handle to watchdog");
    return;
  }

  // Set the watchdog timeout
  ioctl(WatchdogHandle, WDIOC_SETTIMEOUT, &WatchDogTimeout);

  emit signalAddStatusText("Watchdog timeout set to 30sec");

  // Kick the dog
  KickTheDog();
}

//******************************************************************************
**
// Kicks the watchdog (wakey, wakey)
//******************************************************************************
**
void cWatchdog::KickTheDog(void)
{
    // Kick the dog
  write(WatchdogHandle, "V", 1);
}