DB Restored to New Server, ODBC Says Database is Not Valid

I'm setting up a replacement server for SQL 2000 and have restored a DB from old server to new server using backup/restore. All seems to work, DB listed in Enterprise Manager, I can see data. When I try to setup an ODBC connection on same server, however, the DB is not listed in drop-down list and if I enter the name, it responds with "the database entered is not valid". What is left to do?
Detaching the database and then attaching it solved this problem.