Ked,
Frustration can arise from not seeing the results one expects in the given time frame one has set for themselves.
Best to let that feeling of frustration go, it is not an indicator of your ability to PR. If fact, it probably was meant as a lesson of which Alex has given some great suggestions.
I sense that this particular time, there was a sense of being rushed and some form of immediate expectation which led to some form of stress which led to frustration when the desired results did not show up ... agian, only you can know what the lesson to be learned was, I'm just sensing.
As for floundering with PR, that usually is an indication that you are about to make a major breakthrough, stick with it. This is your test as to whether you graduate to the next level.
Michael