AnalogWrite only works on P1.6?

More fun with LEDs!  I took the Energia LED fader example from energia.nu and  modified it to output to P1.4, P1.5, P1.6 and P1.7 so that all four LEDs would fade in sync.

#include "Energia.h"


void setup();
void loop();


/*
 	 http://energia.nu/Tutorial_Fade.html
  Fade

  This example shows how to fade LEDs on pins (P1.4 thru P1.7)
  using the analogWrite() function.

  This example code is in the public domain.

*/

int brightness = 0;    // how bright the LED is
int fadeAmount = 5;    // how many points to fade the LED by

void setup()  {
  // declare pins P1_4 through P1_7 to be outputs:
  pinMode(P1_4, OUTPUT);
  pinMode(P1_5, OUTPUT);
  pinMode(P1_6, OUTPUT);
  pinMode(P1_7, OUTPUT);
}

void loop()  {
  // set the brightness of the LEDs:
	analogWrite(P1_4, brightness);
	analogWrite(P1_5, brightness);
	analogWrite(P1_6, brightness);
	analogWrite(P1_7, brightness);

  // change the brightness for next time through the loop:
  brightness = brightness + fadeAmount;

  // reverse the direction of the fading at the ends of the fade:
  if (brightness == 0 || brightness == 255) {
    fadeAmount = -fadeAmount ;
  }
  // wait for 30 milliseconds to see the dimming effect
  delay(30);
}

Problem: it doesn't work. Or rather, P1.6 fades in and out as it should, but P1.4, P1.5 and P1.7 just turn on and off.

If I change the original Energia code example to fade P1.5 instead of P1.6, the same thing happens: the LED just turns on and off.

I've looked all over for a statement saying that Energia's AnalogWrite only works on P1.6, but have found nothing.  What gives -- is my code broken?

Thanks!