That's a URL it's not a permalink.
Try this:
/@impactn-donation/steem-and-gaia-draper-university-hackathon-how-to-incentivise-social-impact-by-using-steem-blockchain
That's a URL it's not a permalink.
Try this:
/@impactn-donation/steem-and-gaia-draper-university-hackathon-how-to-incentivise-social-impact-by-using-steem-blockchain
Tried it - same result. Doesn't seem to like my link. :-(

Try this.
steem-and-gaia-draper-university-hackathon-how-to-incentivise-social-impact-by-using-steem-blockchain
That's how I got mine to work. Credit to @brianphobos for letting me know.
Many thanks @buzz.lightyear. This finally worked. Definitely a case for the FAQ - I even googled what a permalink is and didn't get a clue.
the Permalink has to be submitted like this to go through properly.
steem-and-gaia-draper-university-hackathon-how-to-incentivise-social-impact-by-using-steem-blockchain
If you put the /@impactn-donationor any of that it will fail.