class dependencies and namespace

Hi,

I am trying to solve an issue with a dependency between two classes as
shown below :

atlwince.h (declaration and definition is done in the .h)
----------

struct _ATL_AYGSHELL_STATE
{
public:
    // Handle initialization and cleanup of AYGSHELL
    _ATL_AYGSHELL_STATE()
    {
        if (!AYGSHELL::SHSipInfo(...)) <- Not yet defined
        {
            m_nAygshellUIModel = Smartphone;
        }
        else
        {
            m_nAygshellUIModel = PocketPC;
        }
    }
};

const _ATL_AYGSHELL_STATE& ATL_CDECL _AtlGetAygshellState();
BOOL WINAPI AtlIsAygshellSupported();
int WINAPI AtlGetAygshellUIModel();
BOOL WINAPI AtlIsDRAEnabled();
void WINAPI AtlEnableDRA(BOOL bEnable);

namespace AYGSHELL
{
    inline BOOL SHSipInfo(UINT uiAction, UINT uiParam, PVOID pvParam, UINT
fWinIni)
    {
        const _ATL_AYGSHELL_STATE& aygshellState = _AtlGetAygshellState();
        ASSERT(aygshellState.m_pfnSHSipInfo);

        return aygshellState.m_pfnSHSipInfo(uiAction, uiParam, pvParam, fWinIni);
    }

}// namespace AYGSHELL

As you can see I have a mutual dependency bewteen these two classes.
When I compile I get :

  error C2653: 'AYGSHELL' : is not a class or namespace name