c++11 share_ptr as value a map key

I just insert pValue to map next i get it from map ,and its value should be 20 ,but not, why?

typedef  shared_ptr<BaseObject> PtrValue;
class CodeExecuteContext{
     public:
     map<string,PtrValue> varIdentPool;
};  



class BaseInteger :public BaseObject{
    public:
        int value;
        BaseInteger(int val):value(val){
            enumObjType = INT;
        };
};

...

PtrValue pValue = rightNode->executeCode(context);
context.varIdentPool.insert(make_pair(leftNode.idName,pValue));

BaseInteger * baseInteger = (BaseInteger *) pValue.get();
cout << "==AssignmentASTFork==  insert [ " << leftNode.idName << " , " << baseInteger->value << " ]" <<endl;

map<string,PtrValue>::iterator it;
for (it = context.varIdentPool.begin() ; it!=context.varIdentPool.end();it++) {
    BaseInteger * baseInteger = (BaseInteger *) it->second.get();
    cout << "[key : " << it->first << ", value : " << baseInteger->value << endl;
}

result:
==AssignmentASTFork== insert [ arg , 20 ]
[key : arg, value : 32742]