It would seem that this is a flash issue.
Check and see if you are using the "Pepper Flash"....if so you need to disable it and use a flash version without the "Pepper" prefix.
The pepper flash causes (for some players) the power / meter bar to keep going after the `ding` line resulting in a late hit.
Try looking in the FAQ`s on how to disable it.
Hope this helps...below:-
https://www.google.com/url?q=http://www.wgt.com/forums/t/190370.aspx&sa=U&ei=IOyUU_7NK8fgOIePgYAI&ved=0CBIQFjAG&client=internal-uds-cse&usg=AFQjCNFedeBXhnr-HwtuO0MfFxgdBenh9w
Listee