unable to sell melee weapons or open the sealed weapon cases

I can't seem to be able to open the sealed weapon cases and after some searching of the similar errors, the search pointed me to mods I don't seem to have installed.

Can anyone help me pinpoint where is the problem with my install pls?

forgot to mention the 2 server mods are the SAIN Server Mod and Softcore Mod

On top of that I cant seem to buy any further things. Greeted with error 1505, stash is full, despite the fact that I have copious amounts of stash space.