What is the text you're pasting into the OWE Validator? I've found it works fine (and I've used HKG in it too). Perhaps it's a problem with the way you're formatting it; you need to use the three-letter airport codes, and a single "-" with no spaces around it to separate them. "," can be used when a surface segment is required.

I have been told that surface segments are counted as a segment within the ticket, but I don't think the OWE validator counts them as such. Was the person telling me this wrong; i.e. do surface segments count as a regular segment towards the limit of 20?