Trying To Access MSSQL Server 7 using PHP4.0.3pl1 on Redhat Linux 7

I'm using Freetds to access the MSSQL server and that works great, trouble is, in order to do it with PHP 4.0.3pl1, I have to recompile PHP and add the flag --with-sybase-ct=/usr/lib/freetds. When I run that I get an error saying the command "ld -lsybtcl" failed. I've done a locate on the server and found the "libsybtcl.a" and "libsybtcl.so" files in "/opt/sybase/lib", I've added this directory, along with "/usr/local/freetds/" to "/etc/ld.so.conf" and run "ldconfig", but "ld -lsybtcl" still fails - any ideas? Chris.