it is luck. u have to use many elixirs until u get max.
for level 1 elixir u should get +2 for max,
for level 2 elixir u should get +3 for max,
for level 3 elixir u should get +4 for max and so on

Acclaim 9D forums suxs. BIGTIME. If anybody promises to give game updates here, I swear I will not go in there anymore.