MFP Device:Printing job was pended when scanning

[Horky Chen]

Dear all,
We have a MFP device(Interface 0:Printer, Interface 1:Scanner), we built Mac TWAIN driver and CUPS driver for scanner and printer. We meet following problem:
OS:Mac 10.4,10.5
1. Start a printing job via USB include 10 pages
2. Start to scan via USB when printing
3. Printing job will be hold. (<NG) Error message sounds like cannot communicate with printer.
4. If you plug out the cable and plug in it again, the job can be resumed.

Would you please give me some comments about it?

Thanks & Best Regards!
Horky