IDS2000 disallows nulls into INT fields of Stored Procs?

Hi, We're converting to IDS2000 and we receive the following error when calling a stored procedure with a null value in an Integer input parameter field: Value exceeds limit of INTEGER precision This proc worked well in Informix 7.3. The field was defined as NULLS = Yes to allow Nulls. This value was updated into the database later into the stored proc. But, it's failing coming in. If we do dbaccess we ARE still allowed to do an update of a value stated as NULL or "", so it's not failing at the update. If anyone has experienced this and found a solution other than changing the stored proc I'd appreciate your comments. Maybe there's a database parameter which would avoid us having the massage the data coming into the stored procedure?? Thank you, Michel