Xcode 6.1: Colour missing using ofxChart within ofxCocoaGLView

I have a large app, in which I’d like to incorporate a number of 3D line plots.
I decided to use the addon: ofxCocoaGLView to show the view within the app. I have followed the example-empty Xcode project, and then introduced the addon: ofxChart to the view.
Unfortunately, my code will not generate colours, however the same code within an example ofxChart project does produce colour.

As a test for the - (void) draw routine in subclass of ofxCocoaGLView, I tried this

  • (void) draw
    {
    ofNoFill();
    ofSetColor(255, 127, 0);
    ofxChart::ofTorus(self.mouseX, self.mouseY, 0, 200, 50);

      //fake back wall
      ofSetColor(20, 20, 20);
      glBegin(GL_QUADS);
      glVertex3f(0.0, ofGetHeight(), -600);
      glVertex3f(ofGetWidth(), ofGetHeight(), -600);
      glVertex3f(ofGetWidth(), 0, -600);
      glVertex3f(0, 0, -600);
      glEnd();
    
      //fake wall
      ofSetColor(50, 50, 50);
      glBegin(GL_QUADS);
      glVertex3f(0.0, ofGetHeight(), 0);
      glVertex3f(ofGetWidth(), ofGetHeight(), 0);
      glVertex3f(ofGetWidth(), ofGetHeight(), -600);
      glVertex3f(0, ofGetHeight(), -600);
      glEnd();
    

}

The torus from ofxChart shows in colour, but the fake walls are black and shades of gray.

I’m new to openFrameworks & OpenGL and quite stumped.