If you have issues when filing, the only thing that matters to the person on the other end of the phone is whether or not the computer will take it. There are some situations that are finicky, but not necessarily legal or illegal. My understanding is that the computer won't accept direct to an airway, because there is not definition of how to get there. Basically, if you can navigate it, you can file it...but even that's not 100% correct.

In the future, filing from airport to a fix that you can adequately navigate to will work. Also remember that the way you file is not necessarily the way you will fly...only what to expect AND what you will do when lost comm. The most practical, real world way to do it is to file to a fix first, then continue via the airway that defines the fix. Even if that takes you slightly out of the way, once you get in radar contact you will probably be able to request a more direct route. Of course, the only penalty to that is that you may not get more direct and you will have to be prepare to fly the way it was filed and have enough fuel to legally conduct the flight the way it was filed.