为什么下面的程序出错？（在python2.5里）
我试过import Tix,没有报错啊。

Traceback (most recent call last):
  File "2.py", line 54, in 
    tkRoot = Tix.Tk( )
  File "/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/lib-tk/Tix.py",
line 210, in __init__
    self.tk.eval('package require Tix')
_tkinter.TclError: can't find package Tix

代码是：
from __future__ import with_statement   # <-- Python 2.5 ONLY
import Tix
import time

class SplashScreen( object ):
   def __init__( self, tkRoot, imageFilename, minSplashTime=0 ):
      self._root              = tkRoot
      self._image             = Tix.PhotoImage( file=image )
      self._splash            = None
      self._minSplashTime     = time.time() + minSplashTime

   def __enter__( self ):
      # Remove the app window from the display
      self._root.withdraw( )

      # Calculate the geometry to center the splash image
      scrnWt = self._root.winfo_screenwidth( )
      scrnHt = self._root.winfo_screenheight( )

      imgWt = self._image.width()
      imgHt = self._image.height()

      imgXPos = (scrnWt / 2) - (imgWt / 2)
      imgYPos = (scrnHt / 2) - (imgHt / 2)

      # Create the splash screen
      self._splash = Tix.Toplevel()
      self._splash.overrideredirect(1)
      self._splash.geometry( '+%d+%d' % (imgXPos, imgYPos) )
      Tix.Label( self._splash, image=self._image, cursor='watch' ).pack( )

      # Force Tk to draw the splash screen outside of mainloop()
      self._splash.update( )

   def __exit__( self, exc_type, exc_value, traceback ):
      # Make sure the minimum splash time has elapsed
      timeNow = time.time()
      if timeNow < self._minSplashTime:
         time.sleep( self._minSplashTime - timeNow )

      # Destroy the splash window
      self._splash.destroy( )

      # Display the application window
      self._root.deiconify( )


#--------------------------------------------
# Now putting up splash screens is simple



# Create the tkRoot window
tkRoot = Tix.Tk( )

with SplashScreen( tkRoot, 'splashImage.jpg', 3.0 ):
   initializeMyApplication( )
   buildTheGUI( tkRoot )

tkRoot.mainloop( )