DbProviderFactories.GetFactoryClasses() do not work when I uninstall odp.net

I am using DbProviderFactories.GetFactoryClasses() method to check odp.net exists or not. It works perfectly fine when odp.net is not installed or when it is install开发者_运维百科ed. But when I unistall odp.net 10g then also it shows odp.net provider exists. I have checked registry it doesn't show odp.net. Please suggest a better way to check if odp.net exists or not.

Check the machine.config's in folders like C:\Windows\Microsoft.NET\Framework\v4.0.30319\Config and C:\Windows\Microsoft.NET\Framework\v2.0.50727\CONFIG .

What do you see in element ? :

Something like this?

  <system.data>
    <DbProviderFactories>
      <add name="Oracle Data Provider for .NET" invariant="Oracle.DataAccess.Client"
        description="Oracle Data Provider for .NET" type="Oracle.DataAccess.Client.OracleClientFactory, Oracle.DataAccess, Version=2.112.1.1, Culture=neutral, PublicKeyToken=89b483f429c47342" />
     .....
    </DbProviderFactories>
  </system.data>