Why doesn't Talk Shoe allow me to upload a previously downloaded talk shoe episode?

I had a community call tonight. It went great, but I could not get the end button to work at all. I finally refreshed the page (I am on Safari) and then I was able to end the call. I downloaded through iTunes the call and trimmed the dead air time off (it was a couple of minutes). Now I can't re-upload it I get a message saying that it's not a format talk shoe uses. How can that be? I changed the length, but I kept all of the other information intact when I trimmed. Help. :)

Also, I use MP3 trimmer -- is there a better way to trim out errors that will make future uploads easier?