When I try to use the "bootfrom" cheat code listed in "knoppix-cheatcodes.txt in the CD or DVD to boot from an iso image on my hard drive I get a message "could not find kernel image on ..."

This happens with Vers4.0.2 on a Win98SE machine and Vers5.1 on a WinXPhome machine.

In the Win98SE machine, the iso file is on a second HD in folder "My Documents/Knoppix/" and is that used to produce the CD.
At F3 boot: I enter bootfrom=/dev/sdb1/My Documents/Knoppix/K*.iso

In the WinXPhome machine, the iso file is on a third partition of the HD in folder "Knoppix/" and is that used to produce the DVD.
At F3 boot: I enter bootfrom=/dev/sda3/Knoppix/K*.iso

Both versions boot up & work correctly without pressing F3.

Any advice?