What am I missing?

[Matt Yule]

I'm new to C++ in general and g++ in particular.  I keep getting the
same type of
error and can't figure out why.  The test program below along with the
error I get when
I try to compile it is typical of the problems I've been having.  I have
a Borland C++ compiler
on my PC at home which compiles the same program with no errors or
warnings.  Am I missing something obvious?  Any help would be greatly
appreciated.

ERROR:
test.cpp: In function `int main()':
test.cpp:35: no match for `TestClass& = TestClass' operator
test.cpp:21: candidates are: TestClass TestClass::operator=(TestClass&)

PROGRAM:
#include <iostream>
using namespace std;

class TestClass {
    public:
        TestClass(int i);
        TestClass(const TestClass &copyme);
        TestClass operator=(TestClass &original);
        TestClass operator+(TestClass &addme);
        int data;
};

TestClass::TestClass(int i){
    data=i;
}

TestClass::TestClass(const TestClass &copyme){
    data=copyme.data;
}

TestClass TestClass::operator=(TestClass &original){
    data = original.data;
    return *this;
}

TestClass TestClass::operator+(TestClass &addme){
    TestClass temp(0);
    temp.data = data + addme.data;
    return temp;
}

int main(){

    TestClass ob1(4), ob2(2);
    ob2 = ob1 + ob2;
    cout << "Object 2 contains " << ob2.data << endl;

    return 0;
}