Potty Training And Pics (...not of potty training)

I uploaded some more pics of the kittens and of my other housecats if anyone is interested: http://www.flickr.com/photos/50555492@N05/

I am having a potty training setback. I enlarged their play area (I uploaded a photo). I can't give them total run of the room because I have some work out equipment in there and I'm afraid they'll try to climb up it, it's pretty tall. But they have about 18 square feet.

Someone has started going #1 in the corners of the play area. I think it's the orange male, I see the gray female going #1 in the litter box frequently.

I keep their box clean and change to fresh litter every day - I remove the #2 as soon as they make it.

We're 100% good on #2 - always in the box for both.

Do I need to put a 2nd litter pan in there? Or change the litter everytime someone goes #1?

They were both 100% for #1 and #2 for over a week - this just started when I doubled the size of their play area.

Any suggestions?

Awwww! They're adorable! Your tabby looks like a torbie with the orange spots! I have a little torbie girl too and some orange boys .
Anyway, the play area looks great for them, with plenty of space to run around. I will tell you, from experience, that in a few weeks they won't stay in there . They love to climb things like gates- they think it's an awesome game.
Perhaps try moving the box or getting another one and putting it in the corner where the little guy has been going to the bathroom. Other than that just be constantly putting him in there after he eats, wakes up, etc.
Have fun with those cuties!