Adding Source Directories

I created a new GUI and I cannot get it to link. Here is the targets.torque.mk entry:

SOURCE.GAME.GUI=\
        game/gui/guiGridCtrl.cc

It compiles fine, but will not link. Where do I tell the engine about the directory it is in?

Here is the output when it fails to link:

--> Compiling game/gui/guiGridCtrl.cc
--> Linking out.GCC3.DEBUG/AetherWizard_DEBUG.bin
out.GCC3.DEBUG/game/gui/guiGridCtrl.obj(.text+0x17): In function 'GuiGridCtrl::G uiGridCtrl[not-in-charge]()':
console/console.h:110: undefined reference to 'vtable for GuiGridCtrl'
out.GCC3.DEBUG/game/gui/guiGridCtrl.obj(.text+0xc5): In function 'GuiGridCtrl::G uiGridCtrl[in-charge]()':
game/gui/guiGridCtrl.cc:22: undefined reference to 'vtable for GuiGridCtrl'
out.GCC3.DEBUG/game/gui/guiGridCtrl.obj(.text+0x1d4): In function 'cGuiGridCtrlp erformClickcaster':
game/gui/guiGridCtrl.cc:44: undefined reference to 'typeinfo for GuiGridCtrl'
out.GCC3.DEBUG/game/gui/guiGridCtrl.obj(.text+0x26a): In function 'cGuiGridCtrls etTextcaster':
game/gui/guiGridCtrl.cc:50: undefined reference to 'typeinfo for GuiGridCtrl'
out.GCC3.DEBUG/game/gui/guiGridCtrl.obj(.text+0x302): In function 'cGuiGridCtrlg etTextcaster':
game/gui/guiGridCtrl.cc:56: undefined reference to 'typeinfo for GuiGridCtrl'
collect2: ld returned 1 exit status
make[1]: *** [out.GCC3.DEBUG/AetherWizard_DEBUG.bin] Error 1
make: *** [default] Error 2