Can't open xliff file in project

SDL Trados 2015 is supposed to support xliff files, but when I add the xliff file sent by a client it says the file type is "unknown" (the file type is checked in the list of file types in the Options, I've checked several times) and no batch tasks are available. On the computer I was able to convert the xliff to a Word document so I can see the text, but delivering the translation in Word would be unacceptable for the client. I've tried fiddling with some of the settings but SDL Trados doesn't even recognize it as a workable file, so that hasn't changed anything. Is there any way to make it work?