I solved my problem by using this line:

if(tmp=="PassDialog") { //QLabel* lbl = f->findChild<QLabel*>("lblRFID"); MyDialog *tempDialog = qobject_cast<MyDialog*>(f); tempDialog->AcceptCard(output); // emit recRFID(output); return; }

and clean that connection and comment the emit code. now its worked.
But I don't know why that code has error.