Check which character set your VB application is using. Ideally you should be using the same character set as the database server. If you're not something needs to do character set conversion; either your application or the connectivity library (Open Client / ODBC).
Find out from your DBA what the is the default character set of the server. If you can, work with that character set. I think Windows uses ISO_1, but other platforms (HP UX for example) use "Roman 8" which is different.
Sorry for the delay but I'm away from home and the office and the hotel has just got wi-fi. The character set that VB is using is probably "iso1", however the character set being used to talk to the database server may be specified when setting up the connection. I'm assuming this can be done within the DSN or connection properties.