Hi
The sales pipeline report is an odd / old report now that has been in crm for many versions. To be honest, I'd spend my time enhancing dashboards than bother with this SSRS Report.
However, in short, it needs workflow in order to display meaningful data. Have a read of this tutorial;
http://rc.crm.dynamics.com/RC/2011/en-us/online/5.1_CTP/salesworkflow.aspx
Rob
MCTS. GAP Consulting Ltd. Microsoft Community Contributor Award 2011 & 2013