Weird behavior from STL map when using custom key class

Hi guys,

I have a weird problem with STL the map, when using my own class as
the key. The code below works correctly when the indicated line is
commented out, but the find method (apparently incorrectly) says that
it can't find a known item -- even though the [] operator sucessfully
retreives it.

The weird thing is that when I enable the copy constructor, it breaks
the find method, but the copy constructor is never actually called!
What on earth is going on? (And how can I fix it and still keep my
copy constructor?)

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

class Angle
{
public:
         double theta;
         bool operator<(const Angle &rhs) const {return
(theta<rhs.theta);}
         Angle(double _theta) {theta=_theta;}

         //uncommenting the following line breaks map.find, even though
the cout string is never printed??
         Angle(const Angle &rhs) {theta = rhs.theta; cout<<"called
copy"<<endl;}
};

class Configuration
{
public:
         double x;
         double z;
         Angle th;

         Configuration(double _x, double _z, double _th) : x(_x), z
(_z), th(_th) {}

         bool operator<(const Configuration &rhs) const
         {
                 if (x!=rhs.x) return (x<rhs.x);
                 else
                 {
                         if (z!=rhs.z) return (z<rhs.z);
                         else return (th<rhs.th);
                 }
         }
};

int main()
{
         map<Configuration,int> m;

         Configuration c2(8,3,1);
         m[c2] = 7;

         if ( (m.find(c2)) == m.end()) cout << "not found" << endl;
         else cout << "found" << endl;

         cout << m[c2] << endl;

         Configuration c3(6,6,6);
         if ( (m.find(c3)) == m.end()) cout << "not found" << endl;
         else cout << "found" << endl;

         cout << m[c3] << endl;
}

---
Output when copy constructor is commented out:
../test
found
7
not found
0
-----
Output when it's uncommented:
not found
7
not found
0
-----

Any help appreciated!
Charles

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