Compile error on templated STL map class

I have a class template (ExclusiveMap) which takes two type parameters
C1 and C2 and declares two private members map<C1, C2> and map<C2, C1>
(both STL maps). In test code I instantiate this class template
providing types int and string for C1 and C2 respectively.

The test code compiles cleanly using GCC 3.2 however when I pass it
through HPUX aCC I get error messages about the inability to convert
strings to ints.

I can appreciate that aCC might be stricter than GCC in certain
aspects however I cannot understand how GCC would compile and link it
with no errors or warnings resulting in an executable that actually
does what I want whereas aCC quits with errors, not just warnings.

Can anyone see what might be causing aCC to require conversion from
string to int in the code below?

test.cc:
=====

#include <ExclusiveMap.h>
#include <string>
#include<iostream>
using namespace std;

class FloeLog
{

public:

    void init();

private:

     ExclusiveMap<int, string> _logTypeMap; // aCC does not seem to
like
// ExclusiveMap<int, int> _logTypeMap; // No compile errors

}; // class FloeLog

void FloeLog::init()
{
    cout << "Inside FloeLog::init(), about to do _logTypeMap.insert()
\n";

      _logTypeMap.insert(12, "FLOE_EVENT");
// _logTypeMap.insert(12, 13); // No compile errors
}

int main()
{

FloeLog FL;

FL.init();

return 0;
}

ExclusiveMap.h:
============

#include <map>
using namespace std;

template <class C1, class C2>
class ExclusiveMap
{
public:

    ExclusiveMap();

    bool insert(const C1& c1, const C2& c2);

private:

    map<C1, C2> _map1;
    map<C2, C1> _map2;
};

template <class C1, class C2>
ExclusiveMap<C1, C2>::ExclusiveMap()
{
}

template <class C1, class C2>
bool
ExclusiveMap<C1, C2>::insert(const C1& c1, const C2& c2)
{

     typename map<C1, C2>::iterator map1Iter = _map1.find(c1);
     typename map<C2, C1>::iterator map2Iter = _map2.find(c2); // This
causes compile error when using HP aCC

     if (map1Iter == _map1.end() && map2Iter == _map2.end())
     {
       _map2[c2] = c1;
       _map1[c1] = c2;
        return true;
     }
    return false;
}

% g++ -g -I. test.cc
<compiles and links without errors>

% /opt/aCC/bin/aCC -AA -c -g -I. test.cc
Error 226: "/opt/aCC-3.30.01/include_std/rw/tree.cc", line 492 # No
appropriate function found for call of 'operator ()'. Last viable
    candidate was "bool std::less<int>::operator ()(const int &,const
int &) const" ["/opt/aCC-3.30.01/include_std/functional", line
    167]. Argument of type 'const
std::basic_string<char,std::char_traits<char>,std::allocator<char> >
&' could not be converted to
    'const int &'.
          if (!_C_key_compare(__x->_C_key(), __k))
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error 226: "/opt/aCC-3.30.01/include_std/rw/tree.cc", line 500 # No
appropriate function found for call of 'operator ()'. Last viable
    candidate was "bool std::less<int>::operator ()(const int &,const
int &) const" ["/opt/aCC-3.30.01/include_std/functional", line
    167]. Argument of type 'const
std::basic_string<char,std::char_traits<char>,std::allocator<char> >
&' could not be converted to
    'const int &'.
                || _C_key_compare(__k, ((_C_tree_iter&)__j)._C_node-


 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error 556: "./ExclusiveMap.h", line 37 # Unable to generate
specialization "__rw::__rw_tree_iter<std::pair<const
    std::basic_string<char,std::char_traits<char>,std::allocator<char>


    &,__rw::__rw_rb_tree_node<std::allocator<std::pair<const int,int>


    std::basic_string<char,std::char_traits<char>,std::allocator<char>
 


    std::basic_string<char,std::char_traits<char>,std::allocator<char>
 


 
__rw::__rb_tree<std::basic_string<char,std::char_traits<char>,std::allocator<char>


    std::basic_string<char,std::char_traits<char>,std::allocator<char>


    std::basic_string<char,std::char_traits<char>,std::allocator<char>
 


    int,int> > >::find(const
std::basic_string<char,std::char_traits<char>,std::allocator<char> >
&)" due to errors during generation.
         typename map<C2, C1>::iterator map2Iter = _map2.find(c2); //
This causes compile error when using HP aCC
 
^^^^^^^^^^^^^^
Error 440: "/opt/aCC-3.30.01/include_std/utility", line 117 # Cannot
initialize 'const int' with 'const class
    basic_string<char,std::char_traits<char>,std::allocator<char> >'.
            : first (__rhs.first), second (__rhs.second) { }
                     ^^^^^^^^^^^