People Search Setup -- Error

I am trying to get people search to work. When I am crawling a content source with sps3 start address, I am getting the below error:

Error in the Microsoft SharePoint Server People Protocol Handler. ( Object reference not set to an instance of an object. )

I am not sure what is causing this problem. I researched and tried all the suggested solutions but nothing seems to work. How can I check whether I configured everything correctly? Is there a step-by-step guide? I followed this MSDN tutorial so far:

http://technet.microsoft.com/en-us/library/hh582311.aspx

Thanks for any pointers