Bests & Worsts Reviews from Amazon

First use over the weekend. Put it in my digital electric smoker. Let it heat up for a good while before checking temp. Digital had it at 225. This read 180. Bumped it to 235. This barely moved. Then popped it to 250. This thing finally peaked at 200 degrees. Seems to be totally useless. If this were any more expensive I'd go through the trouble of returning it. If the seller/manufacturer thinks this is a defective unit, please, send me another to compare. Thanks.