[Proj] Problem in calling pj_transform with retutn x and y = nan

[Limei Ran]

Hi:

Could someone help me on solving the problem I have in calling 
pj_transform?  I am calling pj_transform to do the projection from our 
GIS software in C.  I obtained PROJ.4 and datum shift grids files.  I 
installed the software on our linux server and tested the software using 
cs2cs.  It works fine with the right output. 

I compiled our software with the built PROJ.4 library using the lines in 
our Makefile:
==============================
#set PROJ.4 libary
PROJDIR=/nas/uncch/depts/cep/emc/lran/soft/proj-4.5.0/exe/lib
PROJ_H=/nas/uncch/depts/cep/emc/lran/soft/proj-4.5.0/src/projects.h

# Library paths
LIBPATH=-L. -L$(PROJDIR)
LIBS = $(LIBPATH) -lspatial -lm -lproj -static
.......
allocator.exe: $(ALLOC)
        $(CC) -o $@ $(ALLOC) $(LIBS)
........
=================================

Our program is compiled without errors with PROJ.4 software. 
In my calling scripts, I set:
setenv PROJ_LIB /nas/uncch/depts/cep/emc/lran/soft/proj-4.5.0/exe/share/proj

The program gives the right projected x and y when from and to 
projections are different, but the datum systems are the same (both 
NAD27, NAD83, ot sphere).  But, if I give different datum for from and 
to projections, the print out of projected x and y = nan.  Here are the 
output lines:
==========================================================================
Input projection:
PROJ args=+proj=lcc+datum=NAD27+lat_1=33+lat_2=45+lat_0=40+lon_0=-97


Output projection:
PROJ 
args=+proj=lcc+datum=NAD83+lat_1=30.000000+lat_2=60.000000+lon_0=-100.000000+lat_0=40.000000+units=m


In Projection: x=1100.000 y=-11200.000    Out: x=nan y=nan
In Projection: x=-25000.000 y=25000.000  Out: x=nan y=nan
===========================================================================

Basically, the data transformation parts did not give me the right 
result even though the program ran without any error.  There are many 
libary files under ./proj/lib directory.  I am wondering whether LIBS in 
my Makefile is correct.  Or, I need to set PROJ_LIB somewhere else.  I 
appreciate any help you might have.

Thanks,

LR