“错误：非静态成员引用必须与特定对象相关”是什么意思？

int CPMSifDlg::EncodeAndSend(char *firstName, char *lastName, char *roomNumber, char *userId, char *userFirstName, char *userLastName)
{
    ...

    return 1;
}

extern "C"
{
    __declspec(dllexport) int start(char *firstName, char *lastName, char *roomNumber, char *userId, char *userFirstName, char *userLastName)
    {
        return CPMSifDlg::EncodeAndSend(firstName, lastName, roomNumber, userId, userFirstName, userLastName);
    }
}
int CPMSifDlg::EncodeAndSend(char *firstName, c