Reporting Services Docs cached when called from webserver

I am having a caching problem running reports from my .NET application.

It happens when I have documents with the same name using different parameters and it doesn't refresh.

i.e.
#1 Core.rdl - running with (default,param1) returns a result
#2 Core.rdl - running with (standard,param2) returns #1s result and does not return the new results

I do not have caching enabled on the report server. I believe I need some C# code to clear this out and none of it is working.

The cache is based on parameter values so you should not need to clear the session. Which version of Reporting Services are you using (2000 or 2005)? Can you paste a code snippet of what you are using?