Python Megawidgets - Pmw.Blt problem

[Bruce Wolk]

Has anyone been able to use the Pmw.Blt megawidget on a Win98 system? 
Pmw generally seems to work ok, but when I try the examples at

http://www.ifi.uio.no/~hpl/Pmw.Blt/doc/

they don't run.  I get errors like

Traceback (innermost last):
  File "C:\PROGRA~1\PYTHON\TOOLS\IDLE\ScriptBinding.py", line 131, in
run_module_event
    execfile(filename, mod.__dict__)
  File "C:\Program Files\Python\Bruce\HelloWorld1.py", line 5, in ?
    g = Pmw.Blt.Graph(master)       # make a new graph area
  File "C:\PROGRA~1\PYTHON\Pmw\Pmw_0_~1\lib\PmwBlt.py", line 260, in
__init__
    Tkinter.Widget.__init__(self, master, _graphCommand, cnf, kw)
  File "C:\Program Files\Python\Lib\lib-tk\Tkinter.py", line 1084, in
__init__
    self.tk.call(
TclError: invalid command name "::blt::graph"

Any ideas?

Bruce