compiling php4 for dynamic use in apache 1.3.19 went succesfull, ldconfig and ld /usr/lib/apache/libphp4.so do not complain about any mistakes and after that reloading apache says:

"Syntax error on line nnn of /etc/httpd/httpd.conf:
Cannot load /usr/lib/apache/libphp4.so into server: /usr/lib/apache/libphp4.so: undefined symbol: sasl_set_alloc"

So, i need a gerneral description about this error, i found occurances all over the buglist and spreading that in several mail lists.
Why is ldd not complaining about undefined symbols, while apache loader does ?
Even seeking that special symbol in all libraries and knowing that there is a valid and accesable library for httpd gives me no idea of what went wrong.
Please submit me a descriptive point of view to that behavior.