Need some tips reagarding the sss example

The communication fails after a while, but it seems to fail at a certian point. I have a Matlab function which transmits 1400 bytes. I'm able to transmit these bytes correctly two times, but something always goes wrong when I try to send these bytes a third time. My sss_exec_command function is as follows:

void sss_exec_command(SSSConn* conn)
{
   int free_rx_space; 
   int bytes_to_process = conn->rx_wr_pos - conn->rx_rd_pos;
    while(bytes_to_process--)
    {
        IOWR_32DIRECT(DDR2_SDRAM_BASE, sdram_addr, *(conn->rx_rd_pos));
        
        sdram_addr++;
        
        conn->rx_rd_pos = conn->rx_rd_pos + 2;
        bytes_to_process--;
    }
    
    free_rx_space = SSS_RX_BUF_SIZE-(conn->rx_wr_pos-conn->rx_buffer);  
      
    counter = counter + 1; 
    
    if (teller >= 255)
    {
        printf("Free buffer space: %d \n", free_rx_space);
        counter = 0; 
    }
  
  return;
}

I don't send back anything, and as you can see from the code above I tried to look at the free buffer space. It printed out the same number every time, 218. I also tried your echo test and it worked fine. Did you have to make changes in other methods than the sss_exec_command() and the sss_handle_recieve() ?