Why would a buck work a scrape....and NOT urinate in it?

Is he not ready to mate (sounds unlikely)?

Trying to assert some sort of dominance issue by removing another buck's scent?

Other?

I've seen several work scrapes.....and even seen (what HAD to be "subordinate" bucks do so in the presence of a more dominant animal) multiple bucks use the exact same scrape in the presence of others.

Why would they work every other aspect of the scrape (licking branch......pawing of ground..) and NOT piss in it?

Thanks.