It may not work if your application hasn’t been even looked at yet. I was able to link my application on the day AOR was generated. Alternatively, if you’re well in between the application process, make sure you’re entering information exactly the same way as you filled out the application forms. If you filled the forms with CAPS on, the same thing needs to happen while linking the application to the portal. Weird but not sure why is it setup that way.
I have tried that too. My parents completed their medicals 2 weeks ago so defintely the app is in progress. Just unsure about linking the GCkey and the app. So annoying.