error in loading rugarch package

Any help with the following issues is greatly appreciated. I am running R on a Mac computer rather than a Windows one.


Donglei Du

Was able to install the 'rugarch? from CRAN without error/warning, but has the following loading error when calling 

library("rugarch")


Error : .onLoad failed in loadNamespace() for 'rgl', details:
  call: dyn.load(file, DLLpath = DLLpath, ...)
  error: unable to load shared object '/Library/Frameworks/R.framework/Versions/3.2/Resources/library/rgl/libs/rgl.so':
  dlopen(/Library/Frameworks/R.framework/Versions/3.2/Resources/library/rgl/libs/rgl.so, 6): Library not loaded: /opt/X11/lib/libGLU.1.dylib
  Referenced from: /Library/Frameworks/R.framework/Versions/3.2/Resources/library/rgl/libs/rgl.so
  Reason: image not found
Error: package or namespace load failed for ?rugarch?