Screencaps for upload

Im going crazy

I'm updating an app and now itines connect has changed for uploading metadata. Anyway I have 3.5 inch and ipad screenshots already but it keeps telling me i have to put 4 inch screenshots up

fine

But it wont let me!!!!

I'm trying to upload png files that are 640x1136 into the bit that says drag here. But when I do nothing happend. If I choose add files and select them nothing happens

what is going on why cant it upload my screencaps?