Thanks Dougho,
After I wrote the previous post, Crucial contacted me back and mentioned the SO-DIMM might not be adequate due to the higher speed it supports 1866MHz, and NUC not supporting dual channel for this speed. So they will replace the memory with one that support 1600MHz, i.e. this one: http://eu.crucial.com/eur/en/d54250wyk/CT5042590
By the way, I am not from Crucial, but the support those guys gave me was very good, and the fact they guaranteed compatibility if one uses their web tools to select the components is also great, that is why they are going to send me another kit. Just hope this time it is the right one :-)
Thanks a lot,
Victor