1. Bought a new ML519 and tried to erase check engine light (code P0420 on Citroen Picasso). the scanner identified the code but couldn't erase it. it says "code erase command send" but nothing happens. With a different (and much simple) scanner it worked perfectly. 

2. Because of problem 1, I tried to update the scanner. Downloaded MaxiSys 2 and the relevant files. but each time the program says "equipment doesn't match".  but it does match.

What I do wrong? maybe the Scanner is faulty (unlikely) or am I doing something wrong?

Thanks!