Trying to create effect of type SDL_HAPTIC_CUSTOM, returns failure code (-1) and message “Haptic error Unable to create effect”.

Is SDL_HapticCustom.data (Uint16*) really supposed to be unsigned if it is a custom signal? Should be able to have negative values as well?

Trying with gaming wheel 'Thrustmaster T300RS Racing Wheel', windows 10.

Call chain is:
[My code]->
int SDL_HapticNewEffect(SDL_Haptic * haptic, SDL_HapticEffect * effect);
int SDL_SYS_HapticNewEffect(SDL_Haptic * haptic, struct haptic_effect *effect, SDL_HapticEffect * base);
int SDL_DINPUT_HapticNewEffect(SDL_Haptic * haptic, struct haptic_effect *effect, SDL_HapticEffect * base)
  --> DI_SetError("Unable to create effect", ret);


[My code in effective]
SDL_InitSubSystem(SDL_INIT_JOYSTICK | SDL_INIT_HAPTIC);
int device_index = 0;
SDL_Joystick* joystick = SDL_JoystickOpen(device_index);
assert(SDL_JoystickIsHaptic(joystick));
SDL_Haptic* haptic = SDL_HapticOpen(device_index);

SDL_HapticEffect* effect = new SDL_HapticEffect;
SDL_memset(effect , 0, sizeof(SDL_HapticEffect));
effect->type = SDL_HAPTIC_CUSTOM;
effect->custom.direction.type = SDL_HAPTIC_CARTESIAN;
effect->custom.direction.dir[0] = 1;
effect->custom.length = 5000;
effect->custom.period = 1000;
const int nof_samples = 1000;
effect->custom.channels = 1;
effect->custom.samples = nof_samples;
effect->custom.data = new Uint16[nof_samples];

for(int i = 0; i < nof_samples; ++i) {
  effect->custom.data[i] = Uint16(0); //Or some generated signal
}

assert(SDL_HapticEffectSupported(haptic, effect)); //All ok!

std::cout << SDL_HapticNewEffect(haptic, effect) << std::endl; //Returns -1
std::cout << SDL_GetError() << std::endl; //prints "Haptic error Unable to create effect"