CMD check puzzle

... you need library(survival) in R code in tests/.  It doesn't happen 
  automatically like it does for examples.

Thanks Thomas, that is exactly the hint I needed.  I had read the "check" part 
of the manual 3 times in vain; once you pointed it out I was able to fine  the 
answer in the manual's description of the 'test' subdirectory.
  
  	Terry T.