You VB application is using a Oracle database, to which u have not connected
Check your settings
Assuming u have a Oracle client installed on your machine
1. tnsnames.ora - this file should contain the server ip, port and SID to which you are connecting to.
U can manually make n entry in this file, or go via Oracle Net8 easy config from start->programs->Oracle
2. check for DSN settings from Start-> Control Panel->ODBC settings . Select System DSN and configure a new DSN
Hope this helps
Chitra