This problem is typically caused by an old date being used as your System Age-Up Date. If you enter a birth date which in combination with the System Age-Up Dates makes the swimmer a negative age you receive this error.
  1. Go to Set-up > Preferences > System Preferences in Team Manager
  2. Complete the following under System Age-Up Date (bottom right)
    1. Type correct date, select date using calendar, or check Always Age-Up To Today box
    2. Click Age-Up to correctly age-up your existing swimmers
  3. Click OK
  4. Attempt to add swimmer again