Reassigning workout type error (Read 35 times)

Hi Eric, I am trying to reorganize my workout types, and am running into the following issue:

1) Options > Manage My Activities > Edit Activity

2) Click to select "Ultra" under workout types

3) Click "delete" and "ok"

4) Under "Please select a new workout type for these workouts", select "LongRun", and click "Assign", and then "ok"

5) I receive the message "An unexpected error has occurred."

Thanks for your help!

MTA: Browser is Firefox ESR 10.0.3

Thank you Eric!