yum install trouble

Hi,

I am trying to install yum in my box (fedora 6). when I run yum, I got
this following message, could you tell what's wrong with it?

Thanks

Dong

----------------------------

yum-3.2.25 $ yum
Traceback (most recent call last):
  File "/usr/bin/yum", line 28, in ?
    import yummain
  File "yummain.py", line 30, in ?
    from yum import _
ImportError: cannot import name _