Try this (untested) instead.
Code:
#include <acknex.h>;
#include <default.c>;


BMAP* bullet_png = "missile.png";
PANEL* panel = NULL;


function main()
{
   video_mode = 7;
   video_screen = 2;

   while(1)
   {
      if((key_p)&&(panel==NULL))
      {
         panel = pan_create("bmap = bullet_png;",1);
         panel.pos_x = 300;
         panel.pos_y = 300;
         panel.layer = 5;
         panel.flags = VISIBLE;
      }
      if((key_r)&&(panel))
      {
         pan_remove(panel);
         panel = NULL;
      }

      wait(1);
   }

}



"There is no fate but what WE make." - CEO Cyberdyne Systems Corp.
A8.30.5 Commercial