Unable to connect to SSRS reports using DNS alias

Hi all,I'm currently working for a customer that is looking to connect to their production SSRS instance using a new load balanced VIP with associated DNS alias rather than the use the SQL cluster network nameAt the moment they use the following URL:http://<SQL network name>/ReportServer_PRODSQL/reportexecution2005.asmxWhat they would like to use is the following:http://<DNS Alias>/ReportServer_PRODSQL/reportexecution2005.asmxBoth the <SQL network name> and <DNS Alias> resolve to the same IP address. Can anyone explain why all attempts to connect to the SSRS instance using the DNS alias only display a dialog box requesting username and password credentials?Regards,Paul