Msoffice Plug-in error while saving file

Hi trouble shooter,
I downloaded the trial version to explore Wordfast Pro in Mac. The problem triggered while saving translated files and it leaves the error message ‘error while saving file’. Why I am not able to save a file? Is this a bug? And also I tried to re-install it several times, but the error persists. Do I need to but the license for Wordfast? Help please.

Error while saving file.
java.lang.IndexOutOfBoundsException: Index 2, Size: 2
