Why doesn't GetIndexParameters return anything?

Question

I'm trying to get index parameter information for indexer properties (to determine whether the indexer has more than 1 indexer field, as a few do). I have a variable pi correctly set to the property (and can read various properties of pi) - however the GetIndexParameters method returns an empty array every time: ParameterInfo[] oParams = pi.GetIndexParameters(); Any idea what's up with this?