You accidentally installed the 64-bit version of the driver, or the installer registered it incorrectly. Solution: Uninstall the driver via Control Panel → Programs and Features. Then download and install the correct 32-bit (x86) version.
Because your legacy application is a 32-bit process. When a 32-bit process asks the operating system for a DSN, it does not look in the 64-bit registry hive or the 64-bit driver store. It looks in the 32-bit compatibility layer, known as WOW64 (Windows 32-bit on Windows 64-bit). The DSN you created in the Control Panel is invisible to the application because you effectively installed it in a parallel dimension. 32-bit odbc driver on 64-bit windows 7
Windows 7 (64-bit) has two separate ODBC Data Source Administrator (ODBCAD32.exe) tools: You accidentally installed the 64-bit version of the
When downloading drivers (such as those for MySQL, PostgreSQL, or Oracle), ensure you select the "x86" or "32-bit" MSI/EXE installer. Most vendors provide both versions on their download pages. 2. Run the Installation Because your legacy application is a 32-bit process
Found in Control Panel > Administrative Tools > Data Sources (ODBC) . This tool only manages 64-bit drivers and DSNs.
To verify that the 32-bit ODBC driver is correctly configured: