Hello Aris.Lappas;

It looks like your version of Step 7, v13, has been updated at some point, probably though a service pack of some kind, so you cannot open a V13.0 program with it.

At ths time, the only updated version of Step 7 you could use is v13 SP2:

https://support.industry.siemens.com/cs/ca/en/view/109311724

If that download does not help you, the only recommendation I would have is to contact a Siemens tech, through a Support Request (link at the top of this page).

Hope this helps,

Daniel Chartier