What am i doing wrong with the multiformatsave extensión?

I’ve downloaded the MultiFormatSave v1.5.0 to save documents in other formats but when i apply the application to the file an error turns up instead.

Error1 on line 126. 
An exception occurred 
Type: com.sun.star.task.ErrorCodeIOException
Message: .

All I can suggest is you contact the developer of the extension, which in this case appears to be Rob Snelders. Unfortunately LO does not currently provide contact details on the extension site for developers. There is a proposal to renovate the extensions site currently being discussed so perhaps in the near future this situation will change.