If using a Terminal
server, the reason for this error may be the following:
When you connect to
a terminal server, by default, the printers attached to your workstation are
“mapped” into the terminal services session . This applies to fax printers as
well.
The cause of the “operation failed”
messages seems to be that when someone with a fax printer defined on their own
computer connects to the Terminal server, there will be two fax printers
defined and this will cause the error.
Also there doesn’t seem to be a way to programmatically select a fax printer
through the objects exposed by Microsoft at this time.
The work-around is to disable Windows
printer mapping on the Terminal server. This can be done through the Terminal
Services Configuration program located in Administrative Tools.