package or namespace load failed for ‘ks’

Hi?Friends?
	I have installed ks package successfully using R version 3.4.2 on Mac 10.12.6. But when I  library it ,  I have the following problem. 

error: package or namespace load failed for ?ks?:
onLoad fails when'rgl'is calculated in loadNamespace ():  
Call: dyn.load(file, DLLpath = DLLpath, ...)
Error: unable to load shared target object:?/Users/sanyu/Library/R/3.4/library/rgl/libs/rgl.so??:
dlopen(/Users/sanyu/Library/R/3.4/library/rgl/libs/rgl.so, 6): Library not loaded: /opt/X11/lib/libGLU.1.dylib
Referenced from: /Users/sanyu/Library/R/3.4/library/rgl/libs/rgl.so
Reason: image not found
	This is the first time I write emails to foreign friends , I hope I can get this helps.
	Wang