The Canucks currently have the 28th-ranked power play, at just 10 percent. There are a few possible solutions to this, one of which is (unsurprisingly) to practice the power play. But assuming they're doing that already, let's explore the others.
The Canucks have Jason Garrison on the point of the power play, whose powerful shot is deadly in these situations. The Canucks need to work on getting the puck to Garrison and get bodies in front of the opposing goalie.
It could also be the case that there is nothing wrong with the Nucks' power play. Perhaps they simply haven't been getting the bounces, and success will come as more opportunities arise. After all, 40 power plays aren't a very large sample size.