The ANA tool, as great as it is, will not always give you all your options. Sometimes you have to establish what trans-Pacific flights (usually the main obstacle) are available, and "reverse-engineer" a door-to-door routing from there.

A fine primer on getting the most from the ANA tool using UA miles is here, courtesy of our own gleff:

http://blogs.flyertalk.com//blogs/vi...ng_premiu.html