Why isn't this working?

[Dodobee]

For some reason, specifically the spring and underwater part (lines 2 and 3) don't work but the player.mo.z - player.mo.floorz (line 1) works fine.

    if player.mo.z/FRACUNIT - player.mo.floorz/FRACUNIT < 256
    or (player.mo.eflags & MFE_UNDERWATER)
    or (player.mo.eflags & MFE_SPRUNG)
    player.heightlimit = false
    elseif player.mo.z/FRACUNIT - player.mo.floorz/FRACUNIT > 256
    and not (player.mo.eflags & MFE_UNDERWATER)
    or not (player.mo.eflags & MFE_SPRUNG) then
    player.heightlimit = true
    end