Linked server(Oracle) problem "Access to the remote server is denied because the current security context is not trusted."

Hi, I have a stored procedure on my sql server that uses a linked server to select data from an oracle database and inserts to a temp table on sql server.

When I create a job to exec the sp I get this error....

Access to the remote server is denied because the current security context is not trusted. [SQLSTATE 42000] (Error 15274).

When the stored procedure is executed in management studio there is no problem.

TIA

sql2008r2

oracle 10g