Event lost when sending through the USB to receiver.

Hi

I am using stm32f103RBT6 Microcontroller For sending timestamp in millisecond through usb to a receiver . The program works fine when when i am testing before sending through usb but after dending through usb in receiver sofware its missing a event (sometime it does lose event and sometimes not). Can anyone please tell me where the problem can be ? It's a big program so i can' upload the whole program. Will really appreciate any help. Thanks

Here is the Fifo stack part

Code (text):
Code (C):

typedef struct FifoStack
{
u16 u16EventTimeStampMSPart; //This variable have only the ms part!!!
u32 u32EventTimeStamp; // This variable have only the s part!!!
u8 u8EventInput;
} SFIFO_STACK;

// Private function prototypes -------------------------------------------------
void UsbConnect(void);
void StackPush(u32 u32EventTime, u16 u16EventTimeMS, u8 u8Input);
u8 StackPop(SFIFO_STACK *psFifoStack);
void GetMessage(u8 *pu8Buffer);
void TaskFilter(void);

// *****************************************************************************
/// @brief Function that saves an event in cell
/// @fn void StackPush(u32 u32EventTime, u16 u16EventTimeMS, u8 u8Input)
/// @param[in] u32EventTime @brief Hora do evento
/// @param[in] u16EventTimeMS @brief Hora do evento, ms part ASIF
/// @param[in] u8Input @brief Número da entrada que gerou o evento
// *****************************************************************************
void StackPush(u32 u32EventTime, u16 u16EventTimeMS, u8 u8Input)
{
if ((s16StackWriteIndex + 1) != s16StackReadIndex) // verifica se há espaço na pilha
{
sFifo[s16StackWriteIndex].u16EventTimeStampMSPart = u16EventTimeMS; //ASIF salva o time stamp na pilha, part MS

sFifo[s16StackWriteIndex].u32EventTimeStamp = u32EventTime; // salva o time stamp na pilha
sFifo[s16StackWriteIndex].u8EventInput = u8Input; // salva a entrada digital na pilha
s16StackWriteIndex++; // incrementa o índice de escrita
if (s16StackWriteIndex >= STACK_SIZE) // torna o índice de escrita circular
s16StackWriteIndex = 0;
}
}

// *****************************************************************************
/// @brief Function that retrieves a cell event
/// @fn u8 StackPop(SFIFO_STACK *psFifoStack)
/// @param[out] psFifoStack @brief Evento
/// @retval TRUE, se ok
// *****************************************************************************
u8 StackPop(SFIFO_STACK *psFifoStack)
{
if (s16StackReadIndex != s16StackWriteIndex) // verifica se há dados na pilha
{
psFifoStack->u16EventTimeStampMSPart = sFifo[s16StackReadIndex].u16EventTimeStampMSPart; //ASIF busca o time stamp da pilha, part MS

psFifoStack->u32EventTimeStamp = sFifo[s16StackReadIndex].u32EventTimeStamp; // busca o time stamp da pilha
psFifoStack->u8EventInput = sFifo[s16StackReadIndex].u8EventInput; // busca o número da entrada digital da pilha
s16StackReadIndex++; // incrementa o índice de leitura
if (s16StackReadIndex >= STACK_SIZE) // torna o índice de leitura ser circular
s16StackReadIndex = 0;
return TRUE;
}
else
return FALSE;
}