Thanks for confirming that it can be found.
The probablitiy does increase though. Each time you do it the probability is 20%, but if you look at a group of attempts your probability goes up. For instance, whats the probability of getting at least one head when you flip a coin two times? Even though you have a 50% chance each time you flip, your sample set for two flips is (TT, TH, HT, HH). So to get at least one head you have a 3/4 or 75% chance. Notice that means there is a 25% chance you won't get a heads which can be gotten from doing 1/2*1/2 (the probability of each individual event).
My thoughts on the 20% in this game are that it's easier to look at what the chances are of not getting a schematic, much like in the scenerio above what are the chances of not getting a heads, which would be an 80% chance. Thus for ten tries would be a .8^10 percent chance of not getting a schematic which is about 10%. After 15 tries that drops to about a 3.5% chance you would not get a schemetic meaning there is a 96.5% chance you would have the schematic.
That's really all just a lot of information to prove that I am just that unlucky.