Receive from PCan USB

Hey

I m working with TMS320F28335 connected to a PCAN usb. what im trying to do is create a program that sends messages from CAN A to PCAN and also receives Messages from PCAN to CAN A. The transmitting of the messagues works fine wheareas when i try to send a message from PCAN to CAN A it never reaches the mailbox. are there any ideas as to why this might happen. I have configured Mailbox 8 as the receive mailbox and mailbox 4 as the transmit one, here s my code:

/*--------------------------------------------------------------------------------------------------------------------*/
//                                   Can A Reception and Tranmition to/From PCAN                                                        //
/*--------------------------------------------------------------------------------------------------------------------*/
// Description:
/* The program configures Mailbox 8 In CAN A to Receive Messages from P_CAN and Mailbox 4 to Transmit to PCAN*/


#include "DSP2833x_Device.h"
#include "DSP2833x_Examples.h"


struct ECAN_REGS ECanaShadow;

Uint16 MessageCount=0;

void main()
{
// Initialize the System

        InitSysCtrl();

//Initialize GPIO for eCan
 
        InitECanGpio();

//Pie Control Registers are initialized to their default state

        InitPieCtrl();

// Enable CPU interrupts and clear all CPU interrupt flags:
 
//        EnableInterrupts();

// Initialize the PIE vector table with pointers to the shell Interrupt
// Service Routines (ISR).
 
        InitPieVectTable();

// Initialize CAN A and CAN B

          InitECan(); 


/*---------------------------------Start Receive and Transmit Configurations Configuration------------------------------*/

// For the Transmit Mailbox Clear The CANTRS register

        ECanaShadow.CANTRR.all=ECanaRegs.CANTRR.all;
        ECanaShadow.CANTRR.bit.TRR4=1;
        ECanaRegs.CANTRR.all=ECanaShadow.CANTRR.all;

// Wait until TRS bit clears

        do
        { ECanaShadow.CANTRS.all=ECanaRegs.CANTRS.all;

            } while(ECanaShadow.CANTRS.bit.TRS4!=0);

//Dissable Mailbox

        ECanaShadow.CANME.all=ECanaRegs.CANME.all;
        ECanaShadow.CANME.bit.ME4=0;
        ECanaShadow.CANME.bit.ME8=0;
        ECanaRegs.CANME.all=ECanaShadow.CANME.all;

//Write Identifier in the Identifier Field
//Mailbox 4
       
        ECanaMboxes.MBOX4.MSGID.all=0x0000BBCC;
        ECanaMboxes.MBOX4.MSGID.bit.IDE=1;
        ECanaMboxes.MBOX4.MSGID.bit.AAM=0;
        ECanaMboxes.MBOX4.MSGID.bit.AME=0;


//Mailbox 8

        ECanaMboxes.MBOX8.MSGID.all=0x0000AACC;
        ECanaMboxes.MBOX8.MSGID.bit.IDE=1;
        ECanaMboxes.MBOX8.MSGID.bit.AME=0;


//Writting the Data Lenght

        ECanaMboxes.MBOX4.MSGCTRL.bit.DLC=8;

//Configure the Mailbox In Receive Direction


        ECanaShadow.CANMD.all=ECanaRegs.CANMD.all;
        ECanaShadow.CANMD.bit.MD4=0;
        ECanaShadow.CANMD.bit.MD8=1;
        ECanaRegs.CANMD.all=ECanaShadow.CANMD.all;

//Enable Mailbox

        ECanaShadow.CANME.all=ECanaRegs.CANME.all;
        ECanaShadow.CANME.bit.ME4=1;
        ECanaShadow.CANME.bit.ME8=1;
        ECanaRegs.CANME.all=ECanaShadow.CANME.all;

//----------------------------------------Start Transmission---------------------------------------------------------//

//Write The message data into the Mailbox Data Field

        ECanaMboxes.MBOX4.MDL.all= 0xAAAAAAAA;
        ECanaMboxes.MBOX4.MDH.all= 0x00000000;

for(;;)
{
        ECanaShadow.CANTRS.all=ECanaRegs.CANTRS.all;
        ECanaShadow.CANTRS.bit.TRS4=1;
        ECanaRegs.CANTRS.all=ECanaShadow.CANTRS.all;

    do{

        ECanaShadow.CANTA.all=ECanaRegs.CANTA.all;

        } while(ECanaShadow.CANTA.bit.TA4==0);


        ECanaShadow.CANTA.all= ECanaRegs.CANTA.all;
         ECanaShadow.CANTA.bit.TA4= 1;
         ECanaRegs.CANTA.all=ECanaShadow.CANTA.all;


    do{

        ECanaShadow.CANTA.all=ECanaRegs.CANTA.all;

        } while(ECanaShadow.CANTA.bit.TA4!=0);
   
    MessageCount++;
 
}

}