Yes please clarify your EV Version. I am assumming you are EV 8 sp1.
It sounds like this could be an issue with the EV Domino Gateway not set up correctly.
check the following:
Details:
To enable authentication for the archive search feature, you need to set up Single Sign-On on the Enterprise Vault Domino Gateway.
The following procedure assumes that you are not using Internet Sites documents. If you are, then use the procedure outlined in the Lotus Domino documentation.
For more detail on how to configure Single Sign-On using Web Configuration, see the following IBM article: http://www-1.ibm.com/support/docview.wss?rs=2272&context=SSTJRP&dc=DA400&uid=swg27002760&loc=en_US&cs=UTF-8&lang=en&rss=ct2272lotus
To configure Single Sign-On:
1. In the Domino Administrator client go to Configuration tab and select Server > All Server Documents view. Select (but do not open) the server document
for the Enterprise Vault Domino Gateway.
2. Click Web and select Create Web SSO Configuration from the drop down box .
* In the Configuration Name field, change the default name to EVLtpaToken.
* In the DNS Domain field, enter the DNS domain of the participating Domino servers.
* In the Domino Server Names field, add all the Enterprise Vault Domino Gateways. If you want Single Sign-On to cover DWA users, then you also need to add the target Domino mail servers.
* Click Keys and in the drop down menu select Create Domino SSO Key. Click OK.
* Save and Close the Web SSO Configuration.
3. While the server document for the Enterprise Vault Domino Gateway is selected, click Edit server.
* Click Internet Protocols tab and then Domino Web Engine sub-tab.
* Change the Session Authentication field to Multiple Servers (SSO).
* In the Web SSO Configuration field select EVLtpaToken.
* Save and close the server document.
http://seer.entsupport.symantec.com/docs/321332.htm
