Blossomgiver, that's odd... suggest you just try again. The "swaps tool" is new, might still have a bug, or it may have just been one of those random glitch thingies.
Go to the "seed swaps" link on the left side (move your cursor down the list; when "seed swaps" changes from blue to green, click!). From there you should be able to see and join the plant swap. If you have trouble, LMK... I'll tree-mail you my phone number and we'll try to figure it out.