Your thoughts on the failure of socialism in Russia?

According to Marxist theory, for socialism and then communism to work, the country (in which it is been applied) needs to of had a period of capitalization to stimulate industrial growth etc. However, Russia was industrially and agriculturally backwards and did not meet the criteria for a socialist rule. Do you think this was the reason for socialist failure in Russia or do you think Socialism is inherently flawed?