Can't add certain files to the Vault, they cannot be resolved.

[Anonymous]

Hi,

Inventor 2015 Pro, Vault 2015 Pro. (No idea what service packs are installed so far. Any easy way to know when and if i need to update?)

I have some problems with assemblies my predecessor made. Every now and then i stumble across unresolved files that don't even exist anymore. 

When loading up the assemblies i get no resolve link screens, but once i'm ready to put them in the vault, it refuses. 

I've googled, and some threads are similar, but none of the options provided there work for me, or i don't know how.

Can i get some help? I probably didn't provide enough info, but just ask away.