XLIFF Manager export failed

Hei,

I am experiencing a problem with exporting sdlxliff file to xliff in Xliff Manager. I am probbably doing something wrong as it is the first time. 
My clinet sent me a source file and a target file in power point for reviewing. This is a direct client. They want one file back in xlf. format.
I aligned both document and after saving it as sdlxliff I was trying to test convert it to xliff to see if the client can open it on their side.

However, I get en error message without any explanation why. 

This is what I was doing. Please, look at the video. Have I done something wrong?

 

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