Upload Video error "junk after document element"

By using:

`media.UploadFile`

it can work well on upload image file and return the attachment id, but when i use this function to upload video file, even the video file was successfully uploaded, but without return attachment id and getting this error:

`xml.parsers.expat.ExpatError: junk after document element: line 2, column 0`

How can solve this?