I think Blackberry did not succeed because they did not keep up with the changing technology and they did not adapt to the needs of the consumer. It became harder and harder for Blackberry users to fully interact and communicate with anyone else who did not have a Blackberry.
I also think there were technical issues that caused problems for the company. As the iphone got more popular, Blackberry could not keep up with the amount of services offered. The customer service for Blackberry was also not as good as other competitors, making it even less competitive.