It stops working at this line:

video_mode 7;

Here is the whole thing again:

#include <acknex.h>
#include <default.c>

VECTOR jet_speed;
ENTITY* jet;

function main()
{
video_mode 7;
set(pSplash,VISIBLE);
wait (3);

printf("test");
fps_max = 140;
level_load("riverbed.hmp");
ent_createlayer("blood_gsmall+6.tga", SKY | CUBE | VISIBLE, 0);
wait (2);
jet = ent_create ("mig.hmp", vector(-400,0,100), NULL);
ph_setgravity (vector(0,0, -386));
phent_settype (jet, PH_RIGID, PH_CUBE);
phent_setmass (jet, 3, PH_CUBE);
phent_setfriction (jet, 80);
phent_setdamping (jet, 40, 40);
phent_setelasticity (jet, 50, 20);
while(1)
{
jet_speed.x = 25 * (key_a - key_d);
jet_speed.y = 25 * (key_w - key_s);
jet_speed.z = 25 * (key_cuu - key_cud);
phent_addtorqueglobal (jet, jet_speed);
camera.x = jet.x - 300;
camera.y = jet.y;
camera.z = jet.z;
camera.tilt = -60;
wait (1);
}
}

i don't know what I did wrong or I would fix it. I don't get the black screen, just an error message. up until this point, it displayed both the message you gave me and the black screen.