cant pass url parameters to ssrs report

Hello,

I have tried looking up MSDN which I have found how

http://msdn.microsoft.com/en-us/library/ms155391.aspx

, but it doesnt work when I try and pass customerid = 55309 and auctionid = 44 in the url, which looks like this below:

http://ir-prodsql03/Reports/Pages/Report.aspx?ItemPath=%2fScore%2fRegistration&rs:Command=Renderrc:&Customerid=55309&auctionid=44

doesnt work, is there a setting i need to check?