help needed urgently reg universal driver

Rendering Plug-in for Unidrv is developed to extract data sent to the printer and to block print operation .
We are hooking DrvTextOut() function to capture print data.

We are facing following problems

  1. When print job is sent to the HP LaserJet 4250 PCL 6 remote printer,
    DrvTextOut() is not getting called when printer setting ???print on both
    sides??? option is checked.
    But DrvTextOut () is getting called when this option is unchecked.

  2. When DrvSendPage () is hooked , some PCL XL error ???Illegal operator
    Sequence Operator: EndSession??? is displayed on the print when tested with
    remote printer.

Could you please help us out to resolve above mentioned issue?

We would like to ask you,

  1. Is it right approach?
    This approach will work only for Unidrv based printer drivers .Could you please
    suggest us to make this approach generic for all printer drivers.
  2. Can you please let us the know the statistics of the usage for universal
    driver and other drivers used for printing?