PHP4 as DSO on HP-UX 10.20?

Hi, I try to compile and install PHP4.0.4 on HP-UNIX (Apache server) I want a dynamic module (DSO) : - ./configure runs OK (except 2 warnings because I don't use bison, but Yacc is OK) - make is also OK but doens't generate any .so file (like libphp4.so) - make install seems to create 2 files in the "libs" directory : libphp4.la and libphp4.sal and then fails reporting that libphp4.sl is not a DSO file like this : apxs -i -a -n php4 libs/libphp4.sl apx:Error: file libs/libphp4.sl is not a DSO Any idea ? where should I check ? Why do I get .sl file and not a .so file ??? Thanks for your help, Arnaud