GPS Bee and Seeeduino Stalker

Hi,

I'm trying to use a GPS Bee with a Seeeduino Stalker2.0, but I'm not able to obtain nmea string, either in the bee slot and using a seeedstudio xbeeShield. No problem when I link an xbee module in these 2 places.
No problem when I use a GPS Bee with a regular Arduino and a XbeeShield.

Here the code I use:

/*
Program that read a char from serial port and turn on a led (pin 13)
 if the char was H. Put it low is the char is an L
 */
 
 /* parallax code */
 
//int ledPin = 13;
 
#include <Wire.h> 



char string[32];
char byteRead;

int ledPin = 13;                  // LED test pin
 int rxPin = 0;                    // RX PIN 
 int txPin = 1;                    // TX TX
 int byteGPS=-1;
 char linea[300] = "";
 char comandoGPR[7] = "$GPRMC";
 int cont=0;
 int bien=0;
 int conta=0;
 int indices[13];
 /*------------------------------------*/




void setup() {
  // initialize serial communication:
  Serial.begin(9600);
  /* parallax code */
  for (int i=0;i<300;i++){       // Initialize a buffer for received data
     linea[i]=' ';
   } 
   
  // initialize the LED pins:
 // pinMode(ledPin, OUTPUT);
}


void loop() {
  
   digitalWrite(ledPin, HIGH);
   byteGPS=Serial.read();         // Read a byte of the serial port
   if (byteGPS == -1) {           // See if the port is empty yet
     delay(100); 
   } else {
     linea[conta]=byteGPS;        // If there is serial port data, it is put in the buffer
     conta++;                      
     Serial.print(byteGPS, BYTE); 
     
     
                        
     }
   }  

  /*
  
  
  // read the port:

 int availableBytes = Serial.available();
for(int i=0; i<availableBytes; i++)
{
    string[i] = Serial.read();
} 
Serial.print(string);
Serial.println();
   } */

Thank you for any opinion!

Marco.

No suggestion?