"And it came to pass after these things, that the butler of the king of Egypt and his baker had offended their lord the king of Egypt. And Pharaoh was wroth against two of his officers, against the chief of the butlers, and against the chief of the bakers. And he put them in ward in the house of the captain of the guard, into the prison, the place where Yosef was bound. And the captain of the guard charged Yosef with them, and he served them: and they continued a season in ward." (Bereshis 40:1-4)
A superficial reading of the story of Yosef HaTzadik often leads to many misconceptions about the story. A good example is the excerpt above. Generally people believe that Pharoah imprisoned two people, that they had dreams and that Yosef correctly predicted the outcome for both.
The Malbim, on the other hand, brings a different conclusion from a very precise reading of the text. Look carefully at the first two verses and we find four different titles:
3) chief of the butlers
4) chief of the bakers
The Malbim concludes that there were four people imprisoned in the story, for four different reasons.
The midrash as to what happened to lead to this is well known. Gravel was found in Pharoah's bread and a fly was found in his wine. The Malbim notes something which no one really considers but is obvious once mentioned. The chief baker probably didn't do much baking. The chief butler probably didn't pour the wine himself. Both were tasked merely to present the final product to Pharoah and each had a staff to do the preparations for him.
So who's since was greater? Well, from the perspective of the chiefs, the chief butler's sin was. After all, if the chief baker's job was simply to present the bread to Pharoah, how was he supposed to know there were stones in it? Yes, he should have done a better job supervising his underlings but his failing wasn't like the chief butler's who should have noticed the obvious, that a fly was swimming in the goblet he was about to hand to his ruler.
From the perspective of the underlings, on the other hand, the seriousness of the sin is reversed. The baker is now in the worse position since he should have checked his flour before baking it and noticed the gravel. The butler, on the other hand, could have missed the fly dropping into the wine, something not as serious.
As a result, it matters very much whose dreams Yosef interprets. If we are looking at it from the position of the chiefs, then the chief baker should be the one expecting a good interpretation whilst the chief butler should be dreading what will happen to him. Yet we see that when Yosef reads their dreams, he comes to the opposite conclusion. Against reason, he predicts the chief butler will be exonerated and the chief baker will be executed. This would have been logical had he been speaking to the underlings but not to the chiefs.
The Malbim concludes that this was necessary to prove that Yosef's interpretations were not simply a result of strategic thinking or good luck. By predicting the opposite, he showed that his power to interpret dreams really did come from a higher source.
It seems to me that this reasoning might explain why Yosef was then punished to spend another two years in jail after he asked for help in getting out from the chief butler. This is curious since asking for help is exactly what Yosef should have done! After all, Jewish tradition and law don't require us to sit back and say "I'll do nothing to help myself, God will provide" (the doninant kollel culture's attitude notwithstanding). We are expected to help ourselves when we need to and trust that God will arrange the best possible outcome. Yet here the opposite happened with Yosef being punished for not waiting.
But the hint as to why comes from the Malbim's understanding of the episode with the chiefs. Yes, the logical thing to do was to ask the chief butler for help. However, having just shown that the logic of Man is nothing compared to the plans of God, Yosef should have sat back and realized that just as logic would not result in the right interpretation of dreams, logic would also not get him out of jail. God was clearly arranging events to bring them to their proper conclusion and he was to sit put and wait for things to happen. Having missed this, he was left to sit in jail for two years further.