map inside map in C++

I have a difficult time creating nested maps in C++.

First of all I have typedefed my types

typedef std::map<std::variant<int, std::string>, std::variant<int, long long int, std::string>> SimpleDict;
typedef std::map<std::variant<int, std::string>, std::variant<int, std::string,std::vector<SimpleDict>,SimpleDict>> ComplexDict;

Then I define my map:

ComplexDict m = {
        "MAC0", {

                {"TAG0", "111001011000"},
                {"SEQ", "110000100100"},
                {"IOD", "0000"}

        }

};

However I get No matching constructor for initialization of 'ComplexDic. Even if I change the type of m to std::map< std::string, std::map<std::string, std::string> > for simplicity, I get the same error. I think I'm doing something wrong with the syntax. Could you help?