Alchemy doubt

Ok, here's my doubt:
Imagine I have a +9 weapon and I use an ADV Elixir type B (+2). Now I have a +11 weapon.
Now, imagine I try to make it +12 but it fails and returns to +0 (+2, if you count the ADV)
According to this scenario when I try to make my weapon +XX, will it be harder to succeed?

Main Question: Do ADV elixirs make alchemy harder on lower "+"?

the concept is just the same when your current item is:
+2 (without adv elixir) and you're doing +3 = +2 (with adv elixir) and you're doing +3

I think that the server "doesn't count" the advanced elixirs. Meaning, if you have +9 without adv elixir and try to make it +10, you have the same chance as with +11 with adv B.

P. S. I'm not sure of this, this is just something I've heard of.

Thank you both! (altough you gave me contradictory answers xD)