Having some problem when working on crystal reports

Question

http://dotnetmentors.com/reporting/crystal-report-with-stored-procedure-parameter-and-visual-studio.aspx

Hi......
The above the article(link) is about using store procedure in crystal reports with parameter, it is working fine for the first post back but the problem is when I am selecting Ddl agian and clicking Getreport button for next time it is asking for the parameters again(Enter values(popup),please help me to solve this problem and if possible improve the code for multiple parameters.

Thanks,
Shashi kiran Jillepally