Can't load Rgraphviz on windows-based R

Hi, 
 
I have problem loading Rgraphviz. Following the instructions specified by the README in Rgraphviz_1.20.3.tar.gz didn't help either. 
 
o. set the following Windows environment variables accordingly
   (control panel -> systems -> Advanced -> Environment Variables ):
   (a) create new user variables:
     GRAPHVIZ_INSTALL_DIR   (e.g., C:\Graphviz-2.21) <-------------------------- I stated C:\Graphviz-2.21 (I also tried C:\/Graphviz-2.21)
     GRAPHVIZ_INSTALL_MAJOR (e.g., 2)                <-------------------------- I stated 2    
     GRAPHVIZ_INSTALL_MINOR (e.g., 20)               <-------------------------- I stated 21   
     Notice the way "\/" are used for the paths above.
   (b) add to user variable 'path': $GRAPHVIZ_INSTALL_DIR/bin
     e.g., C:\Graphviz-2.21\bin                      <-------------------------- I stated C:\Graphviz-2.21\bin (I also tried C:\/Graphviz-2.21\/bin)

library("Rgraphviz")

Error in inDL(x, as.logical(local), as.logical(now), ...) : 
  unable to load shared library 'D:/PROGRA~1/R/R-28~1.0/library/Rgraphviz/libs/Rgraphviz.dll':
  LoadLibrary failure:  The specified module could not be found.

In addition: Warning messages:
1: closing unused connection 4 (D:/PROGRA~1/R/R-28~1.0/library/Rgraphviz/libs/Rgraphviz.dll) 
2: closing unused connection 3 (D:/PROGRA~1/R/R-2.8.0/library/Rgraphviz/libs/Rgraphviz.dll) 
Error : .onLoad failed in 'loadNamespace' for 'Rgraphviz'
Error: package/namespace load failed for 'Rgraphviz'

file.exists("D:/PROGRA~1/R/R-28~1.0/library/Rgraphviz/libs/Rgraphviz.dll")

[1] TRUE

sessionInfo()

R version 2.8.0 (2008-10-20) 
i386-pc-mingw32 
locale:
LC_COLLATE=English_United States.1252;LC_CTYPE=English_United States.1252;LC_MONETARY=English_United States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252
attached base packages:
[1] grid      stats     graphics  grDevices utils     datasets  methods   base     
other attached packages:
[1] graph_1.20.0
loaded via a namespace (and not attached):
[1] cluster_1.11.11 tools_2.8.0