LTSpice simulation problem with calculus of power
You labeled the ground node as X, but the ground is global, it can only have one value: 0 (zero). When you referenced V(X,Y), LTspice cannot find any node Y and so your measurement fails.
Solution: don't assign the same net two, different labels. In the case of GND, it will always remain GND, no matter what, while otherwise the usual action is to consider the last applied label. However, you shouldn't count on this and take care that you just don't assign two different labels to the same node.
Minor question: does your OS not support a print screen function of some sort? The moiree can make it difficult to read.

Maybe a picture will say a thousand words?