Several ideas. For one, it would be a good idea to look at the additional information when available before running off to this forum and reporting that info when you do run off to the forum.
Since you know that your provider does support the parameter, you may need to tell WinBatch the type of the parameter because of some deficiency in the ADO interface's type library. To do that you you prepend the 'i4:' string to the variable name when you pass as a parameter to the execute method.
For Example:
rSet = sCon.Execute('SELECT "Jacobs, Russell" FROM AUTHORS', i4:nAffected)
Hopefully, this will fix your problem.