GUI CL prompting error: "Unable to find all required classes"

When I installed the GUI CL prompting option, I extracted my files to
C:\WDT400 and left the "Use folder names" box checked.  During the extract
process, I received several messages asking about overwriting files (to be
expected) and I accepted the newer version.
I activated "GUI prompting" from "Extras" (and turned on "Highlight line"
too).

After restarting CODE/400 and downloading a CLLE member from the server,
I've found that pressing F1 gives me the "Unable to find all required
classes" error.  Prompting (F4) erases the line.

FYI: I have code installed related to PMR 39111, 500.

I'd appreciate a hint and be grateful for an answer.

Thanks,
rf
Environment: WDT V5R1 w/SP2; Win2K current with MS fixes (SP2).  Server:
V5R1M0.  Connection: WAN.