C:\>svrmgr30

Oracle Server Manager Release 3.0.5.0.0 - Production

(c) Copyright 1997, Oracle Corporation. All Rights Reserved.

ORA-12203: TNS:unable to connect to destination

SVRMGR> connect internal@prb1
Password:
Connected.
SVRMGR>

Why could I be getting the above error when starting Server Manager and am then able to connect?

TIA