dl and Solaris

Hi all, Can someone give me a brief explanation as to why dl() does not work on Solaris? I have built php (snapshot from last Sunday afternoon) and have not trouble loading libphp.so into apache using apxs. Also, libphp.so has dependencies on a number of different .so libraries in my case. So, dynamic loading does work, but not dl(). I do see that I'm not getting HAVE_LIBDL set and so that's preventing me from getting dl(). My question is why? Thanks for any help. --pk