Thank you guys,
pick() function seams to be the right solution for me and the message error disappeared... btw, I have to read your link again because I didn't get the point at all yet!
If I understood well the problem is that now my build method is MINGW; if I go back to MSC9, the ones I used to build up the software, I should avoid this kind of error. Is it right?
In your opinion is better to update my code to the new methods? ...This error seems to be first of many many others!