Default [Q] Replaced lcd digitizer not working

I have broken the screen of lenovo A3000.
I had replaced the touch screen but the touch screen is not working.
The broken touch screen works perfectly.
There is no loose connection. I tried again and again.
Is it because of driver problem or is it because the new touch screen is faulty?
The touch screen seller agreed to send me a new one. But until it arrives, I want to confirm source of problem.
Please help.
Thanks in advance