Ok gave this a try now that I am home from work, with no luck
Here is what happens - With your line added
Both player and target (myself) have full runic power bars.
When another unit is selected then myself again the target bar drops to 0
Without your code
Regardless of who is targeted or when the power bar always shows as being full UNTIL some ability is used that alters the current power (ie. using Death and Decay to generate RP).
Hope this helps some.