Access To The Remote Server Is Denied Because The Current Security Context Is Not Trusted

I am unable to run a stored procedure that accesses a linked Oracle database as a dataset for a deployed report in Reporting Services. I receive the following error:



An error has occurred during report processing.

Query execution failed for data set 'spName'.

Access to the remote server is denied because the current security context is not trusted.



A few facts ...

The report previews fine in Microsoft Visual Studio 2005 Version 8.0.50727.762 (SP.050727-7600) report designer with VS being installed on my local machine and a shared data source referencing Server1
The deployed report on Server2 produces the error
The stored procedure code is similar to the following:

SELECT x.FieldName as OracleField

,y.FieldName as SSfield

FROM OracleLinkedServer..DatabaseName.TableName x

LEFT JOIN Server1.dbo.TableName y

The deployed report runs fine when the stored procedure code is changed as follows. This indicates to me that the problem is truly an Oracle connection issue;

SELECT 'ABC' as OracleField

,y.FieldName as SSfield

FROM Server1.dbo.TableName y

The Oracle database is a linked database on both SQL Server1 and on SQL Server2 database engines. (I don't see where in Server2 Reporting Services I can specify additional server connections.)
I've tried to trick Mr. Reporting Services on Server2 by creating a @L_TempTable in my stored procedure, inserting the data into it, then selecting from a SQL Server1.dbo.TableName LEFT JOIN @l_TempTable, but Server2 still knows I'm trying to get out to Oracle and rewards me with the error.
I can effectively run the Server1 stored procedure script on Server2 through MSSMS -- it's just the deployed report that references the stored procedure that doesn't work
The data source properties of the deployed report are as follows:

Select -- A Custom Datasource

Connection Type: Microsoft SQL Server

Connectoin String: Data Source=Server1;Initial Catalog=DatabaseName

Select -- Credentials stored securly in the report server

Username: UserName

Password: Password

Check -- Use as Windows credentials when connecting the the data source

Check -- Impersonate the authenticated user ...



(Please do not get sidetracked on the 'A Customer Datasource' selection above. I'd rather be using a shared data source, but right now, this is just the way it is.)



Anyone's expertise would be greatly appreciated. We have a great data warehouse but sometimes you just have to go back to the Oracle ERP and slug it out. What do I need to do to get a deployed report to effectively read from a stored procedure that references an Oracle table?



To everyone, thanks for reading!



~ Delora