[R-SIG-Mac] spproj - Error in importIntoEnv

[epifanio epi]

i'm trying to install spproj, but i've this error:

* Installing *source* package 'spproj' ...
creating cache ./config.cache
checking for pj_init_plus in -lproj... yes
checking how to run the C preprocessor... cc -E
checking for proj_api.h... yes
updating cache ./config.cache
creating ./config.status
creating src/Makevars
** libs
gcc-3.3 -no-cpp-precomp -I/Library/Frameworks/R.framework/Resources/ 
include  -I/usr/local/include   -fno-common  -g -O2 -c projectit.c -o  
projectit.o
gcc-3.3 -bundle -flat_namespace -undefined suppress -L/usr/local/lib - 
o spproj.so projectit.o -lproj -lcc_dynamic -F/Library/Frameworks/ 
R.framework/.. -framework R
** R
** save image
ld: warning multiple definitions of symbol _signgam
/Library/Frameworks/R.framework/../R.framework/R(lgamma.lo)  
definition of _signgam
/usr/lib/libSystem.dylib(gamma9.o) definition of _signgam
Loading required package: sp
Error in importIntoEnv(impenv, impnames, ns, impvars) :
	objects 'Sline', 'Sring', 'Srings', 'SpatialRings',  
'getSRpolygonsSlot', 'getSringsIDSlot', 'getSringsSringsSlot',  
'getSringCoordsSlot' are not exported by 'namespace:sp'
** Removing '/Library/Frameworks/R.framework/Versions/2.2/Resources/ 
library/spproj'
Execution halted
ERROR: execution of package source for 'spproj' failed
 >

i've installed proj by source code,
the other R-spatial packages work properly.
have you any suggestion to resolve this error message?

Error in importIntoEnv(impenv, impnames, ns, impvars) :
	objects 'Sline', 'Sring', 'Srings', 'SpatialRings',  
'getSRpolygonsSlot', 'getSringsIDSlot', 'getSringsSringsSlot',  
'getSringCoordsSlot' are not exported by 'namespace:sp'

thank's for any help!
Massimo.