C++ std map no viable overloaded operator[] error

I have this map where the keys are of type MyType and the values are maps of types <std::string, std::string>. I need to access the values. Here's my code:

MyClass::MyClass(std::string aDefaultKey, std::map<MyType,std::map<std::string,std::string>> aTypeKVMap):
                   fDefaultKey(aDefaultKey)
{
    std::map<std::string, std::string> fKVPairMap;
    std::map<MyType,std::string> fTypeKeyMap;

    for (std::map<MyType,std::map<std::string, std::string>>::iterator type_it = aTypeKVMap.begin();
         type_it != aTypeKVMap.end(); type_it++)
    {
        std::map<std::string,std::string> kvPairs = aTypeKVMap[(*type_it).second];
        fKVPairMap.insert(kvPairs.begin(),kvPairs.end());
        MyType type = aTypeKVMap[(*type_it).first];

        for (std::map<std::string,std::string>::iterator kv_it=kvPairs.begin(); kv_it != kvPairs.end(); kv_it++)
        {
            fTypeKeyMap[type] = kvPairs[(*kv_it).first];
        }
    }
}

When compiling, it throws two errors:

no viable overloaded operator[] for type 'std::map >' std::map kvPairs = aTypeKVMap[(*type_it).second];

And

no viable conversion from 'mapped_type' (aka 'std::__1::map, std::__1::basic_string, std::__1::less >, std::__1::allocator, std::__1::basic_string > > >') to 'MyType' MyType type = aTypeKVMap[(*type_it).first]; ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~

How do I fix this?