Error when adding Arena Score System

Can somebody pls help me get rid of this error :(

Code:

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WndWorld.obj : error LNK2019: unresolved external symbol "public: void __thiscall CArenaScore::WorldDrawer(class C2DRender *)" (?WorldDrawer@CArenaScore@@QAEXPAVC2DRender@@@Z) referenced in function "public: virtual void __thiscall CWndWorld::OnDraw(class C2DRender *)" (?OnDraw@CWndWorld@@UAEXPAVC2DRender@@@Z)
WndWorld.obj : error LNK2019: unresolved external symbol "class CArenaScore g_ArenaScore" (?g_ArenaScore@@3VCArenaScore@@A) referenced in function "public: virtual void __thiscall CWndWorld::OnDraw(class C2DRender *)" (?OnDraw@CWndWorld@@UAEXPAVC2DRender@@@Z)
MoverRender.obj : error LNK2001: unresolved external symbol "class CArenaScore g_ArenaScore" (?g_ArenaScore@@3VCArenaScore@@A)
.\..\..\Output\Neuz.exe : fatal error LNK1120: 2 unresolved externals

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