For a moment there was hope. The Arab League's mediation seemed to succeed after Assad had consented to talks with the opposition. He even promised to withdraw his troops from the cities. But then he seemed to do the opposite and increased the army actions against the protests. So what went wrong?
It was the behavior of the opposition. They chose to explain the behavior of Assad as an admission of defeat. And they announced that they would intensify they demonstrations. This was clearly a show of force meant to show that Assad had lost and that they now controlled the cities.
But Assad had not meant it that way. And when confronted with this behavior he had no choice but to stay in the cities. What he meant was a kind of armistice where the protesters kept low key and in exchange the army withdrew.
The protesters would have had little to loose to wait and see whether Assad was really serious. They could always come back on the street. By staying home and waiting they would have shown that they are real democrats who want to solve things with talks. It would have shown maturity and promised well for the future. By instead keeping on the protests they showed that they are only interested in getting power for themselves.