Need help with Javascript for Auto Tab

Using Acrobat X Standard -- I tried using the information from PlanetPDF to get the Auto Focus to go to the next field.

The Fields are named Directions and Directions2.  I put this on the Directions field --   AutoTab(this, event, "Directions2");    --where it said it was to go but it isn't working.  The computer just dings when I hit the limit.  Currently the field is using Comb but tried turning it off just to see if that was the problem and it still didn't work.  I tried saving and using Adobe Reader (instead of preview) to see if it worked and it still didn't.

Any ideas on what I need to check?  I am not well versed in Javascript so thought I would check to see if someone could assist.

Thanks for any help