Post the code for this:

1 - Your declaration of the signal in whatever class it is that "deviceIquiry" is an instance of.
2 - Your declaration of the slot in MainWindow.h
3 - Your implementation of the slot in MainWindow.cpp
4 - The code in your MainWindow constructor where you create the "deviceIquiry" instance and connect it to the slot
5 - Your code from one of the places where you emit the signal.

I did check and my "emit" code executes.
How did you check?