- The ID you're using is not an activity ID but the ID of a user profile.
Please read the instructions here to ensure you have a valid activity ID.
- The activity is not visible for CopyMySport because it is private.
Please read the instructions for copying non-public activities note thatf you the the change privacy level of your activities to on your Garmin Connect account then that only applies to newly uploaded activities to Garmin Connect. Already existing activities on Garmin Connect keep their old privacy level. To get these visible you have to change the privacy level of these individual activities.
If you read and followed the instructions provided above and it still does not work, then please log a ticket at http://copymysports.com/support