This error most often indicates you aren't using the most recent version of the iControl libraries. Hopefully you are using the iControl Assembly for .Net (or library for Java). I can't tell from your code whether it's .Net or Java...
What happens is that for enumarations, the client proxy code that's generated builds a lookup for the values of the enumeration. It could be that an enumeration has been updated on 10.0.1 that that method is returning but you have an older version of the client generated code that doesn't contain the new enum value. This can be corrected by re-compiling the WSDL or updating to our latest iControl library.
Hope this helps...
-Joe