You mentioned that you have cleared the cache file but you also say that there isn't one there. The cache file should be in your users configuration folder for DW. The link here should point you to the correct location.
common_installation_issues.pdf
You should try renaming the configuration folder first, installing UE, then deleting the cache file. Once you do this try applying UE to a new blank php page. Please post back with the result that you get, and if you get a js error please include the entire text of the message for us to examine. Also, what is your OS and DW version?
