fw fetchlogs and fw logswitch

[probso]

My managment station was switched off for a period of time, during part of which I have no logged data from one of my firewalls. To solve this having read the Check Point sk30005 article I ran:
fw lslogs my_firewall

which returned
fw.log

I then ran
fw logswitch

Which generated a new log file with the current date_time.log as its name

To retrieve the file I then ran
fw fetchlogs -f date_time.log my_firewall

This however failed with no usefull error to explain why.
Ideas on how to import this file would be great (I have retrieved it via ftp but don't know how to import it on the managment station).

Cheers

Paul