Writter how to validate digitaly signed document

I am having trouble to validate a digitaly signed document when using wrtter The document appears signed, but writter does no validate it.
I work using OpenSUSE 13.1 32 bits and LibreOffice and I am behind proxy.
What do you Suggest for validating these documents? Can it be acomplished by this version of LibreOffice or should i update it?

There was never version The 4.x ended with 4.4; 5.0 was after that.