Axe can compile the application's code just fine, but it can't calculate the signature, which requires a relatively complicated cryptographic procedure. And calculators check this cryptographic signature when receiving an application and reject the application if the signature is wrong.
However, you can still send the application to a computer. As pimathbraniac mentioned, you need to sign the application on a computer. But (as long as you're on Windows) rather than grabbing the signing program and using it manually, you may find it easier to check out the "Tools\Application Signing" folder in your (extracted) Axe download. As the name of "Drag App Over Me.bat" suggests, just drag and drop the application (.8xk) file onto this to sign it.
