Xcode says my iPhone 3GS with 3.0 is too old.

When I try to enable my iPhone 3GS, with 3.0, for development in the Organizer in Xcode, it quickly says the something like "The OS on this device is too old for iPhone development, Please update to a newer OS". And then almost immediately deletes that and says "Could not support development". This is the stock SDK with Xcode 3.1.3 for iPhone OS 3.0. Am I missing something?