Be sure that you have the most current version of Adobe Reader installed.
Be sure that the "Enable Acrobat Javascript" checkbox is checked in Adobe Reader. This option can be found on the Adobe Reader Edit/Preferences/Javascript menu.
Be sure that the "Automatically calculate field values" checkbox is checked in Adobe Reader. This option can be found on the Adobe Reader Edit/Preferences/Forms menu.
Be sure that the "Show border hover color for fields" checkbox is checked in Adobe Reader. This option can be found on the Adobe Reader Edit/Preferences/Forms menu.
We recommend that the "Auto-complete" feature is turned off in Adobe Reader. This option can be found on the Adobe Reader Edit/Preferences/Forms menu.