Typically two things cause this


--The feed is missing required fields (category, description, etc)
--iTunes is having trouble with submissions


For the second, which as your feed is valid and missing no required fields I believe is the issue, it's a matter of waiting an hour or so and retrying. However, as iTunes is finicky, I double checked the rest of the feed. Your show artwork is too large, so even if they do accept the feed, you will likely at some point run into updating issues. Make sure that artwork is under 500KB in size (it's currently 1,128.99KB).