018-505 is a login failure, so it is not in any way an issue of reaching the Mac itself.
In this case, it could be that the username or password is wrong (actual login failure)
Or it could be that the Share can't be found (Nothing to log into)
And of course it could easily be the firmware, since the one I linked (as step 2) in the thread you refer to is newer than the General release firmware you went and pulled from the driver page.
As for a space in the User/Pass on the Mac, I am not sure on that, it should not be an issue, but it might be anyway, it would take no time at all to simply create a Mac user with full priveledges that is simply User= Scan password = JoeTest to discount it as being the problem (Of course you would need to add it to the folder permissions and reboot (The Mac) before doing the scan
