[R-SIG-Mac] Installing the rgl package

[Manasi Vydyanath]

Hi - I appear to be having some difficulties installing the rgl  
package on my MAC OS. The error message I keep getting is:

Error in dyn.load(x, as.logical(local), as.logical(now)) :
	unable to load shared library '/Library/Frameworks/R.framework/ 
Resources/library/rgl/libs/rgl.so':
   dlopen(/Library/Frameworks/R.framework/Resources/library/rgl/libs/ 
rgl.so, 6): Library not loaded: /usr/local/lib/libpng12.0.dylib
   Referenced from: /Library/Frameworks/R.framework/Resources/library/ 
rgl/libs/rgl.so
   Reason: image not found
Error in library(rgl) : .First.lib failed for 'rgl'
Error in .C(symbol.C("rgl_quit"), success = FALSE, PACKAGE = "rgl") :
	"C" function name not in DLL for package 'rgl'

I have no idea what to make of it, and I really need to install this  
package. I would appreciate any help that you could give me. (I have  
a Tiger MacOS)

Thanks!
Manasi