Why wont this program work. It says that "quit_program" wont work, why?

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

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BMAP* stopnorm = "stopncorrect.bmp";
BMAP* stopclick = "stopccorrect.bmp";

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PANEL* button_pan =
{
pos_x = 0;
pos_y = 0;
button(0, 0, stopclick, stopnorm, stopnorm, quit_program, NULL, NULL);
flags = OVERLAY | SHOW;
}