R-2.0.1 reinstall non-CRAN pkg

I am trying to upgrade to R-2.0.1 from R-1.9 on a Mac running OS X 10.3.

I have some simple packages I wrote myself that have to be reinstalled 
to be recognized as valid packages.  I have been using them for a while 
on earlier versions of R, so didn't expect to have any problems.

I am probably going about this the wrong way?  I simply used

R CMD build mypkgdir

and then

R CMD install mypkgdir.tar.gz

the package installs without any error messages.

however, library(mypkgname) still generates spiteful

	Error in library(mypkgname) : 'mypkgname' is not a valid package -- 
installed < 2.0.0?

messages.

My apologies if answers to this kind of question have already been 
posted.  I have looked over the archived r-help threads for the last 
couple of months.

Best

Anthony Westerling