Trouble with creating ofxBox2dPolygon

Hi,
I have below code in update() function.

poly.clear();
    
poly.addTriangle(ofPoint(199, 199), ofPoint(299, 299), ofPoint(399, 399));

float density = 1.0;
float bounce = 0.1;
float friction = 2.0;
poly.setPhysics(density, bounce, friction);
//poly.triangulatePoly();
poly.create(box2d.getWorld());

and I get the assert ont b2Assert, below since the count is ‘2’?

void b2PolygonShape::Set(const b2Vec2* vertices, int32 count)
{
    b2Assert(3 <= count && count <= b2_maxPolygonVertices);

what am I missing here?