CAN'T Changing Shipping Address..

[yes.unicorn]

I sold an item but the buyer lives in Mexico, a place I don't ship too.

 The buyer has family out in Texas that he would like me to send the product there. Which is more then okay with me since it is the United States;  Unfortunately when I go to create shipping label

to change his shipping address, I am able to change everything except the Country or Region. ( which i kind of important )

I am unsure what to do to solve this issue and get the buyer this item as soon as possible with no more set backs.

Help, thanks!