[Tutor] Pmw BLT help

[Chris Smith]

I'm trying to learn how to use Pmw.BLT to have plotting in some GUIs I 
would like to create. I have a book with some examples but when I run 
the code I get this error message which seems to be related to the 
packages I installed and not my code:

Traceback (most recent call last):
   File "C:\Documents and Settings\Chris & Esther\My 
Documents\Python\Books&relatedcode\Python4ComputationalScience\src\py\gui\plotdemo_blt.py", 
line 105, in ?
     blt = BltDemo1(root)
   File "C:\Documents and Settings\Chris & Esther\My 
Documents\Python\Books&relatedcode\Python4ComputationalScience\src\py\gui\plotdemo_blt.py", 
line 16, in __init__
     self.vector_x = Pmw.Blt.Vector()
   File "C:\Python24\lib\site-packages\Pmw\Pmw_1_2\lib\PmwBlt.py", line 
99, in __init__
     self.tk.call(_vectorCommand, 'create', self._name)
TclError: invalid command name "::blt::vector"

I've read over the installation instructions and even reinstalled the 
software and that didn't help any. Could anyone help me out?

C. Smith