OK, there is a problem with what you are trying to do.
You are trying to export from 720p to 1080i.
I suggest that if you have 1280X720 footage you export at 1280X720. Also, trying to export from Progressive to Interlaced does not make any sense to me.
Try exporting from 1280X720 progressive to 1280X720 progressive. Let us know how that works for you.