Huh? – Canasta: Pro Review

So, I'm new to Cannasta and really enjoy playing, but there are some frustrating points to this app. The most being when it's alright to pull the discard file. The opponent seems to pull randomly if they have the discard in a mend OR in their hand (and less than the 2 it holds me to), but sometimes they'll pull the pile drop the top card and nothing else. I'm blocked from doing the same, so am I missing something? It's hard to learn a game from an inconsistent teacher.
Review by SStamos on Canasta: Pro.