/Trade//Value        - returns all 3 <Value> nodes
/Trade//Value[1]    - also returns all 3 <Value> nodes (why is that ?)
/Trade//Value[2]    - returns nothing (why is that ?)

A number of people have responded already, but from what I can tell, the two that have supplied suggested replacements haven't acknowledged that the <Value> elements are at different depths of the tree. I note that the third <Value> is at level 4 while the other two are at level 3.

So, I suggest that the following will get you the first <Value> in the document regardless of the depth of the element:

(//Value)[1]

Cheers,
Wendell