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store text to nodes

sebz92 (12)
so in this program i have two structs 
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struct node{

	string data;
	node* next;
	node* prev;
};

struct list{
	node* head;
	node* tail;
};


one is just nodes for a doubly linked list and the other one stores head and tail pointer.

I am creating a function that creates the list and returns the list, (which will be a head pointer and a tail pointer). 

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list* read(string fn){
	
	ifstream file(fn);	
	node* no;
	string temp;
	lista* bn;
	bn = new list;	
		
	if (file.is_open()){

		if (bn->head == NULL) //if list is empty
		{
			no = new node;
			file >> no->data;
			no->prev = NULL;
			no->next = NULL;
			bn->head = no;
			bn->tail = no;

		}

		while (file.is_open()){

			no = new node;
			file >> no->data;
			
			no->next = NULL;
			no->prev = bn->tail;
			bn->tail->next = no; //here is where i get the error
			bn->tail = NULL;

			if (file.eof()){file.close();}
		}
		
	}
	else { cout << "Unable to open file"; }

	
	return bn;
	
}


why is this not working?
helios (17574)
Explain line 30.
sebz92 (12)
this is what i have now:

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 no = new node;              // new node created
 file >> no->data;          //data passed to it
 no->next = NULL;        //there is nothing in front of the node 
 no->prev = tailz;        // Behind the new node will be the tail
 tailz->next = no;       // in front of the tail will be the new node
 tailz = no;                // now the new node is the tail 
 tailz->next = NULL; // there is nothing in front of the tail
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