Hi Yuping,
this article could help you:
http://www.webratio.com/learn/learningobject/getting-started-with-the-stored-procedure-unit
Moreover you can try to debug and analize the stored procedure execution. In this case you can refer to these guides:
http://www.webratio.com/learn/learningobject/using-visual-debug-v-72
http://www.webratio.com/learn/learningobject/analyze-error-logs-v-72