Snap during transform can not snap to what I want Why can't I snap the point I chose to the target point. 
I tried for a long time to do this, but no use!

Could some help me? Thanks !
Solution in object mode :


Add an empty
Set snap to vertex option
Grab your empty to the needed vertex of the mesh to be moved
Shift+RMB to select the mesh to be moved additionally to the empty
Then grab them both to the destination