Temperature on new Hearthstone Clydesdale

I have a new Hearthstone Clydesdale wood insert that was just installed 2 weeks ago. December has been colder than normal in Connecticut and we've been burning it almost steadily. We are enjoying it as it gives off a lot of heat. One issue though is that I purchased a Condar Inferno magnetic thermometer and it seems I cannot get it past about 275 degrees. Placed on the body of the insert, the reading only reaches 200 or so. When I place on the door, it gets up to about 275. The fire seems very hot and it's giving off a lot of heat, but I'm wondering if I'm not running it hot enough to burn off the creosote or if the thermometer just reads too low.

I suspect the issue may be that even on the door there is a ridge, so I can't get the magnet fully touching the metal. I've used very seasoned and some newer wood with some moisture, however I cannot seem to get close to the 400 degrees I should be bringing it up to.

Any advice is appreciated.

Thanks for the placement advice. Coincidentally there was another post this evening where another new Clydesdale owner fired up his and he had a good picture of the thermometer placement. Once I put it in the same location, the temp zoomed right up.

Thanks again!