Why didn’t Einstein win the ‘Nobel Prizes’ for his theory of Relativity ?

Why didn’t Einstein win the ‘Nobel’ for his theory of Relativity ?
Einstein’s theory of general relativity was confirmed in 1919 by Arthur Eddington (a Brit, not an American, btw) during a solar eclipse.
Answer by NB:
AFAIK there was only one other observation done at the time, which was inconclusive. As a matter of fact Eddington’s observation made headlines all over the world at the time, so General relativity considered pretty solid at the time.

So why did they give the Nobel to Einstein in 1921 for the photoelectric effect, a much less revolutionary discovery ? 2 reasons
1) The Nobel committee has always been cautious about novelties. This was still cutting-edge science at the time and probably nobody on the committee felt they understood it enough to be 100% for it. If the theory turned out to be wrong it would of course have been a major embarrassment.
2) Alfred Nobel’s will stipulates that the prizes should be given to discoveries who confer “greatest benefit on mankind”. This has led the committee to favor “practical” discoveries over purely abstract ones, and in that respect the photoelectric effect is a better choice.
Source:http://bpsolarpanelnews.com/

Einstein Proposes His Theory of Relativity (1905): In 1905, Albert Einstein was a 26-year-old young man working six days a week in the Swiss Patent Office in Bern. In between work and his family life (he had a wife and son), Einstein worked diligently on his scientific theories. Even with what seems like very little time, Einstein had his most productive and momentous year of revolutionary scientific theories that year.

In 1905, Einstein wrote five articles and had them published in the prestigious Annalen der Physik (Annals of Physics). In one of these papers, “Zur Elektrodynamik bewegter Koerper” (“On the Electrodynamics of Moving Bodies”), Einstein detailed his Special Theory of Relativity.

There were two main parts of his theory. First, Einstein discovered that the speed of light is constant. Secondly, Einstein determined that space and time are not absolutes; rather, they are relative to the position of the observer.

For example, if a young boy were to roll a ball across the floor of a moving train, how fast was the ball moving? To the boy, it might look like the ball was moving at 1 mile per hour. However, to someone watching the train go by, the ball would appear to be moving the one mile per hour plus the speed of the train (40 miles per hour). To someone watching the event from space, the ball would be moving the one mile per hour the boy had noticed, plus the 40 miles an hour of the speed of the train, plus the speed of the earth.

In a follow-up paper published that same year, “Ist die Traegheit eines Koerpers von seinem Energieinhalt abhaengig?” (“Does the Inertia of a Body Depend Upon Its Energy Content?”), Einstein determined the relationship between mass and energy. Not only are they not independent entities, which had been a long held belief, their relationship could be explained with the formula E=mc2 (E=energy, m=mass, c=speed of light).
Source: http://history1900s.about.com/