I think the problem might be that you can make your rides either private or public, and if they are private then only you can download files from them...
I uploaded my DIYxGPS done today to Garmin Connect, and had a look at it.
Then I chose EXPORT
selected GPX
you then get a save dialogue, and I tend to code each file with a reference number, and the date, and save it in a special DIYxGPS file for that ride.
Then I email the organiser and attach the file.
It has always worked for me that way !!
PM me if you are still having problems