Q: problem charging after resetting smc

My macbook air 2011 battery last roughly 2 hours. Searching over the internet for solutions, I found this a page on APple support relating to smc. After following all the recommended troubleshooting, I eventually reset my smc. And, my macbook air have problem charging since. Even if I let the charger on, the charging light will not come on which indicate that it is not charging. Sometimes, it takes half a day before the charging light to be on and charging started.