It's no big use seeing the signals unless you have too much time on your hands. USB will spew out quite some amount of initialization messages, so if you're happy to decode them by hand, this shouldn't be a big problem at all.
This won't help much, because there are just two reasons for this not to work:
1) Hardware error, i.e. wrong components or bad soldering. Since it's such a small amount of connections to make, checking them by hand or even just re-doing it is probably the way to go.
2) Software error, i.e. two-way communication is established, but the device doesn't respond correctly or you're missing a driver for the operating system.
Usually, the OS will complain when you plug in a "bad" USB device, so it's quite interesting to know the message you're getting from the OS.