load C code into R

I am trying to load C routines into R on windows, going through the the
book S programming and the R manual, but I know I am missing some steps.

I created a win32 DLL project in Visual C++ (ver. 6.0).  It consists of one
simple routine named test which accepts one *integer argument and one
*double argument and performs a trivial computation.  The dll is named
test.dll.

In R1022 for Windows, I run

 >dyn.load("d:/programs/library/test/test.dll")
 >testr_function(a,x)

.C"d:/programs/library/test/test",as.integer(a),as.double(x))

These are both accepted, and I can use dyn.unload as well with test.dll.  I
notice that while loaded, Visual C++ cannot recompile test.dll.

But when I try

 >testr(10,x)

I get the message “Error in .C("test", as.integer(a),as.double(x)) :
C/Fortran function name not in load table”.

I know I need a link step, or an install step, but I am missing something
in the instructions.  Perhaps just a quick piece of advice could get me to
the next stage…