Using dl() to load GDBM

Hello, I'm trying to write a PHP script that will use the dba_* functions to store data. However, the admins at the host I'm working on built PHP without any dba libraries. I got the gdbm package, and built the .so file, but when I call dl("libgdbm.so"), I get a message about "it might not be a PHP library". How should I go about dynamically loading a lib? Is there any way to use the dba_ functions without needing to rebuild PHP? Thank you, Nissim Chudnoff