error C2440: '=' : caot convert from 'int (__cdecl *)(T,T)' to 'int (__thiscall binarytree::* )(T,T)

I am trying to devise a program that fills an area of an image. Just for leaing and advancing in C++. However, I have this error which appears to be that I am the only one having this specific error. I basically have three files, all written by me. But I am posting only the relevant one here. I have commented the most relevant lines also. Here is the binarytree class:

#include<cstddef>
#include<iostream>
using namespace std;

template<typename T>
class binarytree {

    struct node {
        T val;
        node* right;
        node* left;
    };

    node** getToLeaf(node* &a, T b);
    typedef int (binarytree<T>::*fptr)(T a, T b); //<- this lines produces a function pointer type
    fptr fp; //<- Here is declaration of the function pointer object

    node* root;

public:
    binarytree();
    //~binarytree();
    void add(T a);
    bool contains(T a);
    void printAscending();
    void printAscending(node* c);
    void printDescending(node* c);
    void printDescending();
    int operatorfn(T a, T b);           //<-This is the default comparison function
    void setComparisonFN(int (*cmpfn)(T a, T b));  //used when client wants to manually set the compfn

};

template<typename T>
binarytree<T>::binarytree() {
    root = NULL;
    fp = operatorfn;//when the object is initialized, function pointer is set to the default operatorfn. I get an error here also.
}


template<typename T>
int binarytree<T>::operatorfn(T a, T b) {
    if(a>b)
        retu 1;
    else if(a==b)
        retu 0;
    else
        retu -1;
}


template<typename T>
void binarytree<T>::printAscending(node* c) {
    if(c->left!=NULL)
        printAscending(c->left);
    cout<<c->val<<endl;
    if(c->right!=NULL)
        printAscending(c->right);
}

template<typename T>
void binarytree<T>::printDescending(node* c) {
    if(c->right!=NULL)
        printDescending(c->right);

    cout<<c->val<<endl;

    if(c->left!=NULL)
        printDescending(c->left);

}

template<typename T>
void binarytree<T>::printDescending() {
    printDescending(root);
}

template<typename T>
void binarytree<T>::printAscending() {
    printAscending(root);
}



template<typename T>
void binarytree<T>::add(T addedValue) {
    node** np = getToLeaf(root, addedValue);
    *np = new node;
    (*np)->val = addedValue;
    (*np)->left = NULL;
    (*np)->right = NULL;
}

//this function is used by the client to manually set their comparison function
//in case their data types can not be handled by the operatorfn function.
template<typename T>
void binarytree<T>::setComparisonFN(int (cmpfn)(T a, T b)) {
    fp = cmpfn; //<- the error occurs on this line
}

template<typename T>
typename binarytree<T>::node** binarytree<T>::getToLeaf(node* & pointerToNode, T valueToGet) {
    if (pointerToNode == NULL ||fp(pointerToNode->val, valueToGet)==0)  //<-in this line, the function
                                                                        //pointer begins its role
        retu &pointerToNode;
    else if (fp(valueToGet, pointerToNode->val)>0)
        getToLeaf(pointerToNode->right, valueToGet);
    else
        getToLeaf(pointerToNode->left, valueToGet);
}

template <typename T>
bool binarytree<T>::contains(T a){
    node** np=getToLeaf(root, a);
    if(*np==NULL)
        retu false;
    retu true;
}

and here is the error I get, I think they all originate from one problem:

1>  Source.cpp
1>c:usersyadidocumentsvisual studio 2012projectsbinary treebinary treebinarytree.h(37): error C3867: 'binarytree<T>::operatorfn': function call missing argument list; use '&binarytree<T>::operatorfn' to create a pointer to member
1>          with
1>          [
1>              T=point
1>          ]
1>          c:usersyadidocumentsvisual studio 2012projectsbinary treebinary treebinarytree.h(35) : while compiling class template member function 'binarytree<T>::binarytree(void)'
1>          with
1>          [
1>              T=point
1>          ]
1>          c:usersyadidocumentsvisual studio 2012projectspaint bucketpaint bucketsource.cpp(45) : see reference to function template instantiation 'binarytree<T>::binarytree(void)' being compiled
1>          with
1>          [
1>              T=point
1>          ]
1>          c:usersyadidocumentsvisual studio 2012projectspaint bucketpaint bucketsource.cpp(33) : see reference to class template instantiation 'binarytree<T>' being compiled
1>          with
1>          [
1>              T=point
1>          ]
1>c:usersyadidocumentsvisual studio 2012projectsbinary treebinary treebinarytree.h(98): error C2440: '=' : caot convert from 'int (__cdecl *)(T,T)' to 'int (__thiscall binarytree<T>::* )(T,T)'
1>          with
1>          [
1>              T=point
1>          ]
1>          There is no context in which this conversion is possible
1>          c:usersyadidocumentsvisual studio 2012projectsbinary treebinary treebinarytree.h(97) : while compiling class template member function 'void binarytree<T>::setComparisonFN(int (__cdecl *)(T,T))'
1>          with
1>          [
1>              T=point
1>          ]
1>          c:usersyadidocumentsvisual studio 2012projectspaint bucketpaint bucketsource.cpp(46) : see reference to function template instantiation 'void binarytree<T>::setComparisonFN(int (__cdecl *)(T,T))' being compiled
1>          with
1>          [
1>              T=point
1>          ]
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