USB VIRTUAL COM PORT

I am using the code:

    psLineCoding->ulRate = 115200;

    psLineCoding->ucDatabits = 8;

    psLineCoding->ucParity = USB_CDC_PARITY_NONE;

    psLineCoding->ucStop = USB_CDC_STOP_BITS_1;

    USBBufferInit((tUSBBuffer *)&g_sTxBuffer);

   USBBufferInit((tUSBBuffer *)&g_sRxBuffer);

   USBDCDCInit(0, (tUSBDCDCDevice *)&g_sCDCDevice);

And when I want to transmit something I send the command:

USBBufferWrite((tUSBBuffer *)&g_sTxBuffer, "OK", 2);

The computer shows me a virtual com port number 37, but when I transmit then computer doesn't receive the characters. What is wrong?

Thanks in advance,

Galbas.