My first suggestion is to make sure that you have rebooted your server once
after the Oracle client installation happened (I have seen some machines
where applications running inside ASP.NET, such as report server, cannot
access the Oracle client without a reboot after the client installation).
Then, if this is RS 2005, you have to apply the following steps:
* make sure the WebServiceIdentity is configured through the RS
Configuration tool; often it is set to the Network Service user. You can
also check it by looking up the <WebServiceAccount> element in the
RSReportServer.config file.
* For the specified <WebServiceAccount> apply these steps on the Oracle
client installation directory (Oracle\Oracle version):
Right-click the directory, and then Properties. On the security tab, add the
<WebServiceAccount> and grant read&execute permission. Important: click on
the advanced button and select "Allow inheritable permissions from the
parent ..." before you click OK!

Note: it is also necessary to grant the account read&execute permissions
that is used to execute the RS Windows Service. For RS 2005, both the RS
Windows Service account and the configured RS Web Service account must have
permissions to access the files of the Oracle client installation in the
file system! On RS 2000, this was generally only needed for the RS Windows
Service account.


-- Robert
This posting is provided "AS IS" with no warranties, and confers no rights.
PS: I guess I should know a few things about RS since I'm
designing/implementing some areas of the product :)

[quoted text, click to view]