I had a similar problem with a Mega 2560 R3, Sainsmart 4.2", and the Elecfreaks v2.2 adapter. Having dug through the UTouch.cpp file, there is a section at about line 30:-
I then used an old library 'ITDB02 Touch Mod' and it now works fine. I found the library deep in the Sainsmart website. It would have been nice for Sainsmart to provide a downloadable library which worked!
Please enter a valid email to subscribe
We need to confirm your email address.
To complete the subscription, please click the link in the
email we just sent you.
Thank you for subscribing!
via Egeo 16