GL_EXT_compiled_vertex_array ?

I am using glDrawElements but it doesn’t work on all the computers I am using.
I tried various demo progs using it and they work ! even if the EXT isn’t present. I checked in the sources if there was something like:
if (extension)
use it
do without
but there isn’t.
I found wglGetProcAddress in codes and tried it but it isn’t this.

Something I don’t understand: in all these codes, the compiled_… extensions are called:
On my SDK, it is SGI instead of EXT ! so I replaced EXT by SGI, but…

Moreover, on my S3 Savage3D, that has the extension, some progs work and others not even if the source looks the same (same init, same function calls)

I tried to compile the samples replacing EXT by SGI and it is working on some machines but not all of them !

Got an idea ?