iTunes card load error code

The message would seem to be self-explanatory. The card is valid for Mexico and, presumably, your Apple ID is signed into a different national store. See If you can't redeem your App Store & iTunes Gift Card, Apple Music Gift Card, or content code - Apple Support.

Note you should not post card codes to a worldwide public forum lest they be abused.

tt2

What store is your Apple ID set to use? iTunes gift cards and codes are only valid in the country they are issued in. Assuming that you're not in Mexico then return it or give it away to someone who can use it.

tt2