Configuration: report is deployed on report server and webpage accesses that report

The code from aspx that hides parameters works fine; it's just the code that shows parameters that isn't working. Linked at http://dropster.org/2zis55ifrw2r/Desktop.zip
Please  find a simple report with 1 parameter without DB access, and an aspx page with 1 button to hide the parameter and 1 button to show the parameter

The hide/show buttons worked fine on the dev server, but show button doesn’t work on either of production servers.

Note that it works fine in if run application in VS as well (not on production because those don’t have VS installed) with access of report on report server

see both projects Web app and RS project linked at http://dropster.org/2zis55ifrw2r/Desktop.zip
 (you really need only report to be deployed on RS server)

Environment:
Dev server: VS 2005 SP1, IIS6, DOTNET 2.0, Win2K3 server SP2
Production config 1: IIS5, DOTNET 2.0, Win2K server SP4, Reportviewer component dll in Bin directory that copied by VS from dev server, report deployed on Win2K3 server, SQL RS 2005 server
Production config 2: IIS6, DOTNET 2.0, Win2K3 server Ent SP2, Reportviewer component dll in Bin directory that copied by VS from dev server, report deployed on same Win2K3 server, SQL RS 2005 server

Thanks in advance!