Problem with honeywell dust sensor HPMA115C0-003 arduino library

Hello all,
I'm using a mega arudino board, with the honeywell dust sensor HPMA115C0-003 hooked up on the hardware serial, Serial 1.
I used the library from mitkor2. The senor keeps reporting 0 on all values.
I made some modification on the 'example' code. Code below.
Any suggestions help. Thank you!

#include <hpma115C0.h>
uint32_t pm1_0,pm2_5,pm4_0,pm10;
HPMA115C0 hpma(Serial1);

void setup() 
{
  Serial.begin(9600);
  Serial1.begin(9600);            
  delay(2000);                      // The delay should be 2000-5000 ms 
  Serial.println("Dust sensor test");
  Serial.println("Starting...");
  hpma.Init();
}

void loop() 
{
  Serial.println(millis());
  hpma.ReadParticleMeasurement(&pm1_0,&pm2_5,&pm4_0,&pm10);
	Serial.println("PM 1.0: " + String(pm1_0) + " ug/m3" );
	Serial.println("PM 2.5: " + String(pm2_5) + " ug/m3" );
  Serial.println("PM 4.0: " + String(pm4_0) + " ug/m3" );
  Serial.println("PM 10: " + String(pm10) + " ug/m3" );
 
  delay(5000);
}

Follow up with additional information. TX and RX lines are on 3.3v, and power is on 5v.