The activities have probably already been marked as sent on the Forerunner 310XT. Try to force send the history from the device to the computer again. There is no way to just force send the one or two activities, the entire history for this device will be sent. Due to the time involved, I recommend deleting all but the most recent 30 days worth of history to shorten this transfer time.
[URL="http://support.garmin.com/support/searchSupport/simpleCase.htm?caseId={7576dec0-7533-11de-5495-000000000000} &kbName=garmin"]How can I resend my history from my wireless watch to my computer?[/URL]
If you continue to experience problems with the transfer, contact Product Support by phone for further assistance.
There may be files from earlier attempts interfering with the sync process. Express stores files in a folder on the computer before uploading them to Connect. Please use the FAQ: Where do my activities go on the computer before they are uploaded to Garmin Connect? to locate files that were not uploaded.
Technically, this folder should be empty after a successful sync. If there are any files there you can try to manually upload them. All files must have the .FIT extension before manually importing into Connect. Use the steps in the FAQ: How do I manually upload data from USB Mass Storage devices to Garmin Connect? to manually import to Connect. Connect will only upload valid activity files that have not already been uploaded. Regardless if Connect accepts the file(s) they should be removed to prevent issues with future syncing.
To prevent future sync issues, delete the watch from Express and Connect, Master Reset it then add it back again. See the FAQ: How do I delete a fitness device from Garmin Express? and How do I master reset my Forerunner 310XT?
If you continue to experience syncing issues, contact Product Support by phone for further assistance.
