Hi Luz Rodriguez
The SQL code itself is OK as I verified.
Your use of isql is confusing.
Is this isql from SAP/Sybase or some other vendor ?
Normally for connecting to MSSQL I use sqlcmd (command line) or MSSQL Studio (GUI).
sqlcmd is similar ( but not same as ) isql from SAP/Sybase
If this does not take you further, you will need to open an incident with SAP.
HTH
Avinash