Stored Procedure returning BLOB data

I'm trying to execute a stored procedure (Informix) that returns at least one column that's a BLOB. I can access all the columns in the resultset except the BLOB. When I do a GetChunk, I get an error: "Invalid cursor position". I've tried using all possible cursor types. The only option that seems to work is dbUseNoCursor. If I use straight SQL instead of the stored procedure, everything works fine. Does anyone know why I can't do a GetChunk on a BLOB column when it's coming back through a stored procedure? Thanks in advance. I'm using VB 5, and RDO 2 to access the Informix DB. -Steve