[Packrat]

If the your Ranger has the quest and the scroll, the gaurds should take it. There are no other conditions.

I always walk through the throne room door and give it to the gaurd on either side.

You might try clicking on 'talk' first. I know I remember them saying...' I can not talk now, I am on duty '..before I gave it to them...Then when I gave it to them, they say ..'Hmmm, what is this? Very interesting..blah, blah, blah..Thank you for delivering it.'

Now that I think about it, I don't remember if they ever actually took the scroll. If they do , their packs might be too full to take it. Either try another guard or click on 'trade'.