大家看一下这个例子我运行以后怎么总是有错误，哪位高手给详细说明下是怎么回事？我是用console Applation 建立的工程 自由格式运行以后出现，
INK : warning LNK4098: defaultlib "LIBC" conflicts with use of other libs; use /NODEFAULTLIB:library
sglui2.obj : error LNK2001: unresolved external symbol _SGLDRAWLINE@16
Debug/76.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.
76.exe - 2 error(s), 1 warning(s)
这是怎么回事啊？源程序如下
module sgl_util
  use sgl
  implicit none
  integer, save :: x=0
  integer, save :: y=0
contains
subroutine display()
  integer, parameter :: size = 10
  call sglClearBuffer()
  call sglColor3i(255,255,255)
! call sglDrawLine(x-size, y-size, x+size, y+size)
!  call sglDrawLine(x+size, y-size, x-size, y+size)
  call sglUpdateBuffer()
  return
end subroutine
subroutine MouseMove(mx,my)
  integer mx,my
  x = mx
  y = my
  call display()
  return
end subroutine
subroutine MouseDown(key)
  integer key
  write(*,"('Push mouse button ',I1)") key
end subroutine
subroutine MouseUp(key)
  integer key
  write(*,"('Release mouse button ',I1)") key
end subroutine
end module
program main
  use sgl_util
  implicit none
  ! 设定鼠标在窗口中移动时, 会调用MouseMove
  call sglMouseMoveSub(MouseMove)
  ! 设定鼠标在窗口按下按钮时, 会调用MouseDown
  call sglMouseDownSub(MouseDown) !
  ! 设定鼠标在窗口松开按钮时, 会调用MouseDown
  call sglMouseUpSub(MouseUp)
  call sglDisplaySub(display)
  call sglCreateWindow(100,100,400,400,1)
  call sglShowCursor(0) ! 隐藏操作系统的鼠标光标
  call sglMainLoop()
  stop
end program