Если юзер SCOTT имеет права на подключение к SDE (см. ArcSDE_Config_GD_Oracle.pdf), т.е. Вы можете подключиться локально на сервере, то возможно проблема вот такая:
http://forums.esri.com/Thread.asp?c=2&f=59&t=81786#2 21134
My problem was caused by Microsoft Firewall Client software. The software was disabled but the winsockproxy.dll was still being loaded from the installed directory. I was able to get SDE to work after the Firewall software was un-installed from the machine using Add/Remove programs dialog
Или
We had the same problem (XDR etc), users could not remotely attach to SDE (Win 2003 server, Sqlserver 2000). The problem was solved by removing IMON. IMON is a mail port watcher component of NOD32 virus checker.