When Darth Sidious aka Palpatine, declared him self emperor of the galaxy he was under the impression that his empire would be ruled by generations of sith to come. But because of his own stupidity and trust in Vader his Empire fell 23 years after it's formation.

In my previous blog I stated that Sidious was a genius, I Think he was until he became emperor.(in case you missed it http://blogs.starwars.com/masteryoda/2)
He made several mistakes that ultimately lead to the fall of his empire.
After his troops couldn't find Yoda's body he said "then he is not dead", but he didn't search every corner of Coruscant to find him, and if he did his attempts were unsuccessful.
He knew Obi-wan had to have been alive, because Padmé' s ship was gone when he arrived on Mustafar. Yet he did not search high and low for him.
If I were Sidious, had my own empire and a huge Army awaiting my command I'd say twenty years is quite enough time to search every single planet in the galaxy.
Why did he not search for them, did he want them to survive

Years later when every one thought he was dead Obi-wan resurfaced yet this did not concern the emperor, the only thing that did concern him was the rebellion and Luke destroying the Death Star. He never thought for an instance that if Obi-wan survived, it was possible that Yoda survived as well.
During his training Luke went of to help his friends in Cloud City, he had to face Vader to do so. After this Vader was obsessed with finding his son, the emperor on the other hand was more concerned with completing his second death star. He did not see Vader's love for Luke until it was to late.
Yoda finished Luke's training by telling him he was ready to face his father and bring him back to the light side. After this, Yoda died. When Luke and Yoda first met the Sith felt a great disturbance in the Force, when Yoda died they sensed nothing. This could be explained as Dagobah's strong dark side aura preventing the sith from sensing it. It could also be that the emperor was not concerned about this, after al he had already for seen his own victory.

The Emperor's Mistake:
He was over confidant, he thought no one could defeat him. He trusted Vader with his life. He made the mistake to underestimate Vader's Love for Luke, he Overestimated his own power to control both Father and Son.

He tried to gain an apprentice, but in the end he lost every ting, thanks to his own stupidity and delusions of his ultimate power. After 23 years the galaxy was finally freed from his tyranny.

Please comment, al agreements/disagreements are more than Welcome.

May The Force Be With You