No columns were returned from the database for table '...'

I'm migrating from a oracle 8.0.5.0 to a SQL 2008 R2.

I'm connected to the oracle server, but when i select a table, it won't receive his columns

This is the output:

     Oracle Server Object Collector error: table : CONTACT
     ORA-01405: fetched column value is NULL
     Loading columns for table or view 'CONTACT' failed.
     Oracle Server Object Collector error: table : CONTACT
     No columns were returned from the database for table 'CONTACT'.