从已有的文件中的二叉树的前序遍历序列为 ABC##DE#G##F###，创建二叉树

template <class T>
void BinaryTree<T>::CreateBinTree (ifstream& in, BinTreeNode<T> *subTree)
{
    T item;
    if(!in.eof())
    {
        in>>item;
        if(item!=RefValue)
        {
            subTree=new BinTreeNode<T>(item);
            if(subTree==NULL)
            {cerr<<"存储分配错误！"<<endl;exit(1);}
            CreateBinTree(in,subTree->leftChild);
            CreateBinTree(in,subTree->rightChild);
        }
    else
        subTree==NULL;
    }
}
void main()
{
    BinaryTree<char> Bin;
    BinTreeNode<char> subTree;
    cout<<"第一题：假设某二叉树的前序遍历序列为ABC##DE#G##F###，请构建二叉树。\n";
    ifstream in("C\\实验四\\data.txt");
    Bin.CreateBinTree(in,subTree);
    cout<<"二叉树创建完成.........................\n";
}
error C2664: 'CreateBinTree' : cannot convert parameter 2 from 'struct BinTreeNode<char>' to 'struct BinTreeNode<char> *'
        No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
这是什么错误啊！求高手解答啊