I have a wired thermometer that I mainly use for roasts, which can support the entire probe inside the meat.  However, I used it last night to cook some country style ribs (pork) and was only able to insert the probe about half-way into the rib.  It wasn't touching any bone and when I calibrated it, it still read true. Anyway, when the alarm went off on the pork (I set the alarm for 160 expecting the temp to coast up to 165), it was still massively underdone. The probe lacks the dimples that I am familar with on my instant read thermometers and I would like to know if anyone has run into a problem like this before.  All I can think is that the heat from the oven was being read off the back side of the probe.  The tool is so useful that I would hate to regulate it to roast only duty but I have no idea how to fix this so it will work accurately.   
I'm going to assume that "country style ribs" are the ones where you cut them apart first before cooking ... I'd wager a guess that everything is near bone, and a thermometer might have problems with this particular dish.  If nothing else, as you can't insert it deeply enough into the thing you're taking a measurement of, there might be enough conduction along the probe for the oven temperature to throw off the reading.  Could you tell us how far the probe was in the meat?  I'd assume anything less than about 1/3 the probe might be problematic, with 1/2 or more being better.  ...  All of that being said, are you sure it's an issue with the placement of the probe, and not a problem with the probe itself?  I've had a number of them go out over the years.  I've actually given up on them, and gone back to an instant read thermometer, as I'm up to 4 of the bases (can still use 'em as a timer), and no working probes.  (if anyone knows any brands that sell the replacement probes individually, or even better in multi-packs, I'd be willing to go back to using them)  To calibrate -- mix some ice water, and put the probe in there.  It should read 32F or 0C.  (if it even goes that low, not all do).  Boil water, and read the temperature of it, and it should read near 100C or 212F (possibly lower, if you're above sea level).  Compare it to another room thermometer after it's been sitting for a bit ... they should read the same.  Don't try to put it into the oven directly ... you could melt the probe ... that's how I lost the first one, so you can't try to compare it to your oven thermometer. 