This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
Okay, now include the code relevant to that error message's creation. If it's similar to the original snippet but uses "longMaper" in the place of "stringMapper" then I don't think it would work, since "id" just makes an input element id.