@数据结构大神：递归遍历二叉树，建立树的代码 为什么错?

 //创建-输入-打印-递归
# include<stdio.h>
# include<stdlib.h>
# include<malloc.h>
typedef struct Node{
 char data;
 struct Node *Lchild;
 struct Node *Rchild;
}BiTNode,*BiTree;

BiTree CreateBiTree(BiTree bt)
{
 char data;int flag=1;

 while(flag)
 {
 scanf("%c",&data);

 if(data!='$')
 {   
     bt=(BiTNode *)malloc(sizeof(BiTNode));
     bt->data=data;
        bt-Rchild=(BiTNode *)malloc(sizeof(bt-Rchild));
     bt->Rchild=CreateBiTree(bt->Rchild); //为啥建立完右孩子之后就return了呢? 
        bt-Lchild=(BiTNode *)malloc(sizeof(bt-Lchild));
     bt->Lchild=CreateBiTree(bt->Lchild);//为啥return后才建立左孩子呢？ 
 }
 else {flag=0;}
 }

 return bt;
}

void Visit(BiTree bt)
{
 while(bt->data!='$')
 printf("%c,",bt->data);
}

void PreOrder(BiTree bt)
{
 if(bt!=NULL)
 {
  Visit(bt);
  PreOrder(bt->Lchild);//全部遍历 
  PreOrder(bt->Rchild);//全部遍历 
 }
}

int main()
{
 BiTNode *bt;
 CreateBiTree(bt);
 PreOrder(bt);
 getch();
}

bt-Rchild=(BiTNode *)malloc(sizeof(bt-Rchild));

你有的没有写指针的访问符！
bt->Rchild