Max31855 Internal temp strange value

I am using a shield with the MAX31855 with the library from adafruit with my arduino duemilanove.
Using the library example "serialthermocouple" I have measurments of the internal temp of the max31855 about 15 degrees higher than it is supost to be
Using a mixure of water and ice that has a temp o 0º I get measurments of the temp os the thermocouple about 15 ºc.
Does this means my shield is broken ? Or am I doing something wrong ?

Thanks in advance

José

Do you have a link to the code?

If the reading is constant 15° too high there might be an error in the code, or there is a need for calibration?
Do you have other readings that confirm a 15° offset? (e.g. room temp, cooking water, body temp 37C etc)

Thanks for the reply
Today I figure out that something is wrong, maybe with the max31855.
I will check and get back with news.

Jose