I want to add something to what JenS said.

 

You also need to name the file in 'Description of file,' at the beg of the PDF Attachments section, 'Form OR-40.'

This is the first time in 29 seasons, I have run into a situation where you couldn't reference the attachment to include the client name. 

I haven't filed every state, and I have filed lots of Oregon returns, but this error (and lack of explanation) is the most frustrating.