make fails to find libncurses.so.5 on Solaris 8

I am trying to compile teTeX 2.0.2 on a Solaris 8 box with the Companion
Software (which provides the SFWncur package), but it's failing during make
with "ld.so.1: ./makedoc: fatal: libncurses.so.5: open failed: No such file
or directory"

/opt/sfw/lib/libncurses.so.5 is the path to this lib, yet all of the following
options have failed during the make cycle:
./configure --prefix=/opt/local/teTeX --with-ncurses-libdir=/opt/sfw/lib
./configure --prefix=/opt/local/teTeX --with-ncurses-libdir=/opt/sfw
./configure --prefix=/opt/local/teTeX --with-system-ncurses

Why is there a "no such file" error when I've explictly defined the path to it?

Adrian