Hi Peter,
You can remove the "DRIVER=Adaptive Server Anywhere 9.0;" portion of this connection string - you are not really accessing the ODBC driver manager through the ADO.NET driver. The SQL Anywhere ADO.NET driver uses another native DLL (dbdata9.dll) to do its communication directly to the server (which also references a language DLL: dblgen9.dll).
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Wen you go to deploy, it will be important that the deployed dbdata9.dll / dblgen9.dll bitness matches the .NET runtime bitness (x86 to x86, or x64 to x64). See KBA 1984310 for more information about this: https://service.sap.com/sap/support/notes/1984310
Please let us know if you run into any other problems.
Cheers,
Jeff Albion
SAP Active Global Support