There are a number of forum posts about code hinting not showing up as expected in Flash CS5 documents. There are a number of possibilities about why code hints do not show up, but the following post will collect some troubleshooting tips that may help you out.
<li>Reset your code-hint cache using the following steps:
- Quit Flash.
- Delete the following folder:
C:Documents and SettingsusernameLocal SettingsApplication DataAdobeFlash CS5languageConfigurationCodeModel
/Users/username/Library/Application Support/Adobe/Flash CS5/language/Configuration/CodeModel