R CMD check error

I have a local library which depends on the expm library.  The expm library is loaded into 
my personal space and I have the environment variable R_LIBS_USER set appropriately.  The 
command "library(expm)" works just fine from the command line, and in fact the package 
works if I do the source() and dyn.load() commands by hand.

The following sequence works:

tmt% R CMD build --no-build-vignettes hmm
tmt% R CMD INSTALL hmm*gz
tmt% R
 > library(hmm)
 >  run some commands from the hmm library

But "R CMD check hmm.gz" fails with
   ERROR: dependency ?expm? is not available for package ?hmm?
* removing ?/people/biostat2/therneau/consult/alzheimer/hmm.Rcheck/hmm?

The R CMD build command fails similarly if I let it try to build the vignettes.

What's up?

Terry T


 > sessionInfo()
R version 3.3.1 (2016-06-21)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: CentOS release 6.8 (Final)