Some gochas that I only found through trial and error are some configuration issues, on the server that is running the reporting server service, make sure that in your file rsreportserver.config has been modified to allow for basic authentication. By default, if I'm understanding it correctly, it wants a more trustworthy connection type, but the sdk needs you to allow simple name and passwords to be passed. This means that needs to be added to your authentication methods in the configuration.
so for example,
In C:\Program Files\Microsoft SQL Server\MSRS11.1\Reporting Services\ReportServer\rsreportserver.config (Different for server and version, but you get the idea.)
<Authentication>
<AuthenticationTypes>
<RSWindowsNTLM/>
<RSWindowsBasic/> ##you need to add this one##
</AuthenticationTypes>
<RSWindowsExtendedProtectionLevel>Off</RSWindowsExtendedProtectionLevel>
</Authentication>
IIRC you will have to restart the service for this to take effect.
Also, if you are attempting to RenderAs, some of the template files used to pop the headers have space in them towards the bottom that will prevent you from rendering as Excel, PDF, ect unless that has been fixed since I worked on it.
I'm looking through the code you provided, I may be reading it wrong, but it looks like you are trying to explicitly define the report you're after in the execution url. If that is in fact what you are doing, I believe the fix would be to only define the report base you are connecting to so for your example the url should be http://172.16.4.63/ReportServer/
. After that connection is made, you would use the LoadReport2 function to specify which report you need.
Lastly, Where you have the name of the report, it looks like you have a subdirectory called testfolder? if that is still the case, you would need your report name to be "/TestFolder/testClaimHdr" in the call to LoadReport2.
Hope any of that helps.