Qt C++ Custom Class for copy and paste on multiple application using QSharedMemory

Question

QT C++ Can I use Custom mime-type for copy and paste on multiple application?

After I asked that question, I tried to make a application using QSharedMemory.

But When I try to copy and paste between A and A'

Can not read memory occured. (In single Application, It works perfectly)

Below are my result and code.

In single application : works great

In multiple application : cannot read memory

My custom class

class CustomVector{
public: vector<CustomData*> vecs;
};

Copy function

sharedMemory.setKey("TestKey");  // setKey to identify
if (sharedMemory.isAttached()) {
 if (!sharedMemory.detach()) {
  QMessageBox msg;
  msg.setText(tr("Unable to detach from shared memory."));
  msg.exec();
   }
}

    CustomVector* from = new CustomVector(); // 

// do some work for adding CustomData* data to from using pushback (omit)
int size = sizeof(*from);

if (!sharedMemory.create(size)) { // create sharedmemory by size of from
            cout << "Unable to create shared memory segment: " <<     sharedMemory.errorString().toStdString() << endl;
            sharedMemory.detach();
            sharedMemory.create(size);
            cout << "detached" << endl;
        }

sharedMemory.lock();
CustomVector* to = (CustomVector*)sharedMemory.data();
memcpy(to, from, sizeof(*from));
sharedMemory.unlock();

Paste function

sharedMemory.setKey("TestKey"); 
sharedMemory.attach();

CustomVector* to = new CustomVector();

sharedMemory.lock();
CustomVector* from = (CustomVector*)sharedMemory.data();
memcpy(to,from, sizeof(*from));
sharedMemory.unlock();

sharedMemory.detach();
// and do some work using pasted CustomVector* to (omit)

How can I copy and paste on multiple application using QSharedMemory and Custom class that includes vector ?