"Invalid 1x Size"?

I’m sure this has been posted previously, but I’m having trouble uploading the specific images to create an emoticon because it says “Invalid 1x Size” There doesn’t seem to be anything wrong with the resolution of the images, as seen here: http://imgur.com/a/btV6E What do I do?

All submissions must be uploaded in three sizes. The sizes, in pixels, are as follows: 28 x 28, 56 x 56, 112 x 112.
Your images are sized, 42 x 42, 84 x 84 and 168 x 168 respectfully.
Scale those to the appropriate sizes and it shouldn’t give you an error.