insert into hash table using linked list

Having trouble in inserting a node in the linked list. The Linked List *p is not NULL always ,therefore I am unable to see the data[index] is NULL or NOT.

created a class for node,linked list and hash table. Problem is that to avoid collisions I am unable to find the data[index} is NULL,where Linked list* data[].

void add(const value_type& val) {

    int index = 0;
    index = hashfun(val);
    LinkedList<value_type>* p = data[index];
    if(p!=NULL) //ALways p is !=NULL is the problem
    {

        data[index]->add_L(val);
    }
    else

    data[index] = new   LinkedList<value_type>();
    data[index]->addToHead(val);



    }

Find whether the data[index] is empty.