i guss this line
Code:
//WITHIN SECTOR RANGE
    if (enemypos_vec.x < my.x + scan_sector.x && enemypos_vec.x > my.x - scan_sector.x &&
     enemypos_vec.y < my.y + scan_sector.y && enemypos_vec.y > my.y - scan_sector.y &&
     enemypos_vec.z < my.z + scan_sector.z && enemypos_vec.z > my.z - scan_sector.z)


should look more like this:

Code:
//WITHIN SECTOR RANGE
    if (you.x < my.x + scan_sector.x && you.x > my.x - scan_sector.x &&
     you.y < my.y + scan_sector.y && you.y > my.y - scan_sector.y &&
     enemypos_vec.z < 10&& enemypos_vec.z > -10)


I guess this should work. This will check all ents between -10 and 10 of height.
You problem was (i guess) that you compared the relative x and y coordinates with absolute x and y coordinates.

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