wal-mart doesn't like american express

Today:

Did an errand run. Needed to buy a few things. Headed to Wal-Mart. Picked up my items. Proceeded to the checkout.

On attempt to use American Express.. "Card Not Accepted".

Huh?

I voided all the items and left.

Same day:

Went to K-Mart. Bought same items. Used American Express card.

Went right thru. No problems at all.

I can only assume Wal-Mart either doesn't accept AMEX cards, or AMEX refuses to do business with them.

K-Mart, on the other hand, accepts just about everything.

Very interesting.